Patent Publication Number: US-7724529-B2

Title: Disk array system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application claims priority from Japanese Patent Application No. JP 2007-091647 filed on Mar. 30, 2007 and Japanese Patent Application No. JP 2007-332718 filed on Dec. 25, 2007, the contents of which are hereby incorporated by reference into this application. 
   TECHNICAL FIELD OF THE INVENTION 
   The present invention relates to a disk array system (also referred to as a storage system) having a function to control a storage device such as a HDD (Hard Disk Drive). More particularly, it relates to a structure and method for a handle, a lever and others for use in operations (actions) of a module such as insertion/removal and fixation thereof. 
   BACKGROUND OF THE INVENTION 
   In a recent disk array system, mounting density has been increased and performance thereof has been improved. Accordingly, higher cooling performance has been demanded in order to cope with the temperature rise due to the increase in heat generation of component parts and resulting performance deterioration. 
   For example, in the disk array system of a predetermined method, elements such as boards (circuit boards) corresponding to various functions and power sources are installed in the system chassis by means of the structure and method of a module (also referred to as a unit, package, and assembly) to take the maintainability into consideration. Further, as a structure and method for operations by a maintenance person such as insertion/removal and fixation of the module, the module is provided with a structure (hereinafter, referred to as operating structure) such as a handle and a lever. Conventionally, the structure and method for operation of the module are different depending on the modules (for example, controller module, power source module and the like) because of the difference in the mounting structure of the system chassis and each module. Further, the module is handled mainly by a maintenance person with knowledge. 
   SUMMARY OF THE INVENTION 
   The structure and method for operations of the module such as insertion/removal and fixation thereof in the configuration of the chassis and module of a conventional disk array system are insufficient in operability because plural types of the structures and methods are mixed. In particular, this is not suitable for the operations by an end user without sufficient knowledge. Further, as another example of the operating structure, the module is fixed to the chassis with screws using a tool such as a screw driver. In this case, since there is a possibility that the screws which constitute the module itself are not operated appropriately, the operability is insufficient. Further, since outer appearance of each operating structure such as shape and color is different, the operability is insufficient. 
   The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technology for realizing the structure and method for operations such as insertion/removal and fixation of the module that can efficiently improve the operability in consideration of the operation by an end user in the disk array system in which high density mounting and cooling performance are taken into consideration. 
   The typical ones of the inventions disclosed in this application will be briefly described as follows. In order to achieve the above-described object, the present invention provides a disk array system comprising a group of storage devices (disk array) such as a HDD and a control device thereof (controller or disk controller), wherein elements such as controllers and power sources are installed in the system chassis by means of the structure and method of a module, and in a redundant configuration in which each function is at least duplicated, each module is inserted or removed through the opening in front or at the back of the chassis and connected to the front or rear surface of a backboard inside the chassis, and wherein technological means and configurations as shown below are provided. 
   According to the present invention, in the disk array system in which high density mounting and cooling performance are taken into consideration, as a structure and method for operations such as insertion/removal and fixation of a module to a chassis, a new operating structure (referred to as operation lever herein) which takes into consideration the operation of an end user is provided on an object module so as to correspond to the structure of the chassis and module. The present invention includes mainly (1) a structure in which common operation levers are provided to plural types of modules, (2) a structure in which common operation levers designed based on a controller module (necessary operation forces are estimated from a connector coupling force (insertion/removal force)) are provided to other various types of modules, and (3) detailed configuration about the number, location, and mounting method of the operation levers, which differs depending on the detailed structure of each module. 
   In the disk array system of the present invention, first, the chassis and module thereof have the following configuration in consideration of the high density mounting and cooling performance. In the basic chassis, a storage device module (for example, SAS HDD) and a battery module are installed from the front surface into the front part of a backboard, and duplex (two) controller modules are installed up and down from the rear surface and duplex (two) power source modules each containing a fan unit (plural fans) are installed in the right and left areas thereof in the rear part. Further, in the expanded chassis, an enclosure module is to be installed instead of the controller module, and a storage device module is installed from the front surface into the front part of the backboard, and duplex (two) enclosure modules are installed side by side in an upper area of the rear part from the rear surface and duplex (two) power source modules each containing the fan unit (plural fans) are installed side by side in the lower area. In the basic chassis, HDD connectors are disposed near the center area in the longitudinal direction of the backboard so as to correspond to the positions of the connectors of the SAS HDDs, and connectors of the controller are disposed near the upper and lower sides of the backboard so as not to interfere with the HDD connectors. Further, the two power source modules are disposed in right and left areas of the two controller modules so as to correspond to the positions near the right and left sides of the backboard. 
   (1) The modules to which the operation levers are provided include five types, for example, a controller module, a power source module, and a battery module of the basic chassis and an enclosure module and a power source module of the expanded chassis. A plurality of storage device modules are excluded from the object for consideration because there occurs no problem in operability if a structure such as its own handle is provided. In this structure, the common operation lever is a latch-type lever which is constituted of a lever main body (rod-like component), a screw fixing portion (rotary shaft portion), a latch portion (fixed latch portion), and a hook portion and applies the principle of leverage. One or more operation levers are attached to predetermined positions of one module in consideration of a force necessary for operation of the module (operation force). The lever main body can be moved up and down with respect to a module surface around a rotary shaft portion as a fulcrum point. The latch portion is hooked and fixed to the structure of a receiving portion on the chassis side or the module side by the latch action when the module is fixed. The hook portion is hooked and fixed to the structure of a receiving portion on the chassis side when the module is fixed. 
   (2) If the structure of the chassis and module is considered in the design of the common operation lever for the above-mentioned modules, the operation force necessary for the operations of insertion/removal and fixation of the module is estimated from a connector coupling force for the connection to the backboard, and for example, the operation force is largest in the controller module of the basic chassis. Accordingly, the structure of the operation lever to be provided to the controller module is determined based on the controller module. Then, that operation lever is applied to other modules in common, that is, all the object modules are provided with the common operation levers. As a condition for the common use of the operation lever, an operation lever (one of two operation levers) of the controller module covers the operation force of an operation lever in other modules. 
   For example, a controller substrate is mounted in the controller module and its connector on the rear surface side is connected to a corresponding connector on the backboard (coupled through connector). The operation force necessary for the operation of the controller module is estimated from the position, number, coupling force, and force balance of the connectors. Then, the operation lever (for example, two operation levers) to be provided in the controller module is designed in accordance with the operation force. 
   Basically, the operation lever is preferably disposed at a position (ideal position) on an extension line (same plane as connector arrangement plane) from the central position of a connector (backboard connecting connector) on the module rear surface to the front surface of the module on an opposite side. One or more operation levers are disposed in an area near the ideal position on the module front surface so as to satisfy the condition of the operation force necessary for the module. It is preferable that the hook portion of the operation lever is disposed at the ideal position. Further, the arrangement of the operation lever at the ideal position is difficult in some cases due to the detailed requirement for module installation. In this case, the operation lever is disposed at a position shifted from the ideal position to its surrounding area. 
   (3) The detailed configuration of the operation levers to be provided to various object modules including the aforementioned operation lever provided to the controller module is determined. Since the installation area, connector coupling force and detailed requirement for mounting differ depending on each module, the difference in the configuration of the operation levers for each module, for example, the number of arranged levers, position and mounting method thereof is determined in detail in accordance with the differences. As for the number of the operation levers to be arranged, an operation lever is arranged if the necessary operation force is satisfied or two levers are arranged if the operation force is insufficient. The arrangement position is a position exposed on a side of an opening of the chassis in consideration of the position of a connector for the connection to the backboard. As for the mounting method of the operation lever component, the operation lever is disposed and mounted inside (in a recessed portion) or outside (on a projected portion) the module area which is substantially box-shaped in its external shape, and alternatively, the receiving portion for the operation lever component is provided in the form of an internal mounting portion (recessed portion) or an external mounting portion (projected portion) in an area on the chassis side or module side. 
   (4) The configuration of the module and operation lever is as follows. By fixing a screw fixing portion of the operation lever at a predetermined position of the module, the module having the operation lever is formed. The operation lever has a lever main body of a predetermined length on one end side relative to the screw fixing portion (rotary shaft portion) which serves as a fulcrum point, a latch portion which is a movable portion at a tip of the lever main body, and a hook portion at a position in a predetermined length on the other end side. The lever main body, screw fixing portion, and hook portion are, for example, an integral structural member. A spring portion is incorporated between the lever main body and the latch portion for the latching action of the latch portion to the receiving portion on the module side or the chassis side. The latch portion is accommodated in the lever main body in a state where it is in contact with the spring portion, and the initial position of the operation lever (latch portion) is determined so that the tip of the latch portion is projected from the lever main body when a part of the latch portion (fastening portion) is hooked to a part (hole portion) of the lever main body. When the tip of the latch portion is pressed by a user or the latch portion is pressed with a rotation of the lever main body, the spring portion is flexed and the latch portion is moved in the length direction of the lever main body, and at the same time, a claw portion which is a part of the latch portion is moved. 
   In the operations of insertion and fixation of the module using the operation lever, the lever main body of the operation lever is moved down relative to the module surface with the screw fixing portion acting as a fulcrum point by a user. Along with the operation (consecutively), an action of pressing the tip of the latch portion is carried out automatically or consciously. Accordingly, the claw portion of the latch portion gets into the receiving portion on the module side or chassis side in the state where the spring portion is flexed, and then it is hooked and fixed (latched) by an elastic force of the spring portion. At the same time, the hook portion on the other end side of the screw fixing portion also gets into the receiving portion on the chassis side and is hooked and fixed. Further, the module is connected to the backboard through a connector in the mounting area in the chassis, and it is fixed securely by the operation lever. In the operation for removing the module and releasing the fixation thereof using the operation lever, the action reverse to that described above is carried out. 
   (5) Further, in this configuration, the operation lever (particularly, lever main body which is an object for rotation action) of each module, which is a portion to be operated by a user, is colored in a predetermined color so as to be distinguished from the module itself to improve the visibility. In addition, the latch portion which is an object to be pressed (shifted) of the operation lever is colored so as to be distinguished from other portions to improve the visibility. Consequently, a portion for the operation (action) by a user becomes easy to find, and the operability can be thus improved. 
   (6) Further, the operation lever has a structure which can be disassembled to respective components easily without any special tool. When disassembling it into components for recycle, a user presses a part (fastening portion) of the latch portion toward the inside through a hole in the front surface of the lever main body of the operation lever. By this means, hooking of the fastening portion to the lever main body is released and the latch portion is detached from the lever main body, and the incorporated spring portion is taken out. 
   The effects obtained by typical aspects of the present invention will be briefly described below. According to the present invention, it is possible to realize the structure and method for operations such as insertion/removal and fixation of the module that can efficiently improve the operability in consideration of the operation by an end user in the disk array system in which high density mounting and cooling performance are taken into consideration. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
       FIG. 1  is a diagram showing a configuration of an information processing system by a disk array system according to an embodiment of the present invention; 
       FIG. 2  is a diagram showing a system configuration by the connection of modules to backboards in a basic chassis and an expanded chassis in the disk array system of the present embodiment; 
       FIG. 3  is a diagram schematically showing a configuration of a power source system in the disk array system of the present embodiment; 
       FIG. 4  is a perspective view showing a hardware configuration of the basic chassis seen from a side of a front surface (A); 
       FIG. 5  is a perspective view showing a hardware configuration of the basic chassis seen from a side of a rear surface (B); 
       FIG. 6  is a perspective view showing a hardware configuration of the expanded chassis seen from as side of a front surface (C); 
       FIG. 7  is a perspective view showing a hardware configuration of the expanded chassis seen from a side of a rear surface (D); 
       FIG. 8A  is a diagram showing a configuration of the front surface (A) of the basic chassis; 
       FIG. 8B  is a diagram showing a configuration of the rear surface (B) of the basic chassis; 
       FIG. 9A  is a diagram showing a configuration of the front surface (C) of the expanded chassis; 
       FIG. 9B  is a diagram showing a configuration of the rear surface (D) of the expanded chassis; 
       FIG. 10  is a diagram schematically showing a planar configuration of the basic chassis in the horizontal direction; 
       FIG. 11  is a diagram schematically showing a planar configuration of the basic chassis in vertical direction (side surface); 
       FIG. 12  is a diagram showing the configuration of the basic chassis seen from the front surface side of the backboard; 
       FIG. 13A  is a diagram showing a configuration of the connection of a HDD module to the backboard of the basic chassis in the case of a SAS-HDD; 
       FIG. 13B  is a diagram showing a configuration of the connection of a HDD module to the backboard of the basic chassis in the case of a SATA-HDD; 
       FIG. 14A  is a diagram schematically showing a planar configuration of a power source module installed in the basic chassis and its periphery in the horizontal direction; 
       FIG. 14B  is a diagram schematically showing a planar configuration of a power source module installed in the basic chassis and its periphery in the vertical direction (side surface); 
       FIG. 15  is a perspective view showing a disassembled state of the structure of a CTL module installed in the basic chassis; 
       FIG. 16  is a diagram showing the basic structure of an operation lever; 
       FIG. 17  is a schematic diagram for describing the basis of the design of arrangement (mounting positions) of the operation lever to the module; 
       FIG. 18  is a schematic diagram for describing the design of arrangement of the operation lever to the CTL module of the basic chassis; 
       FIG. 19  is a schematic diagram for describing the design of arrangement of the operation lever to the power source module of the basic chassis; 
       FIG. 20  is a schematic diagram for describing the design of arrangement of the operation lever to the battery module of the basic chassis; 
       FIG. 21  is a schematic diagram for describing the design of arrangement of the operation lever to the ENC module of the expanded chassis; 
       FIG. 22  is a schematic diagram for describing the design of arrangement of the operation lever to the power source module of the expanded chassis; 
       FIG. 23A  is a diagram showing an example of the mounting structure of respective operation levers to the rear surface of the basic chassis; 
       FIG. 23B  is a diagram showing an example of the mounting structure of respective operation levers to the front surface of the basic chassis; 
       FIG. 24  is a diagram showing an example of the mounting structure of respective operation levers to the rear surface of the expanded chassis; 
       FIG. 25A  is a plan view showing a detailed structure (first structure example) of the operation lever; 
       FIG. 25B  is a plan view showing a detailed structure (first structure example) of the operation lever; 
       FIG. 25C  is a plan view showing a detailed structure (first structure example) of the operation lever; 
       FIG. 25D  is a plan view showing a detailed structure (first structure example) of the operation lever; 
       FIG. 26  is a diagram showing an example of the attachment of the operation lever to the chassis and module and a module fixing state; 
       FIG. 27  is a diagram showing an example of the attachment of the operation lever to the chassis and module and a module fixation released state; 
       FIG. 28A  is a diagram showing the operations of insertion/removal and fixation of the module having the operation levers to and from an area in the chassis by a user and corresponding mechanism; 
       FIG. 28B  is a diagram showing the operations of insertion/removal and fixation of the module having the operation levers to and from an area in the chassis by a user and corresponding mechanism; 
       FIG. 28C  is a diagram showing the operations of insertion/removal and fixation of the module having the operation levers to and from an area in the chassis by a user and corresponding mechanism; 
       FIG. 28D  is a diagram showing the operations of insertion/removal and fixation of the module having the operation levers to and from an area in the chassis by a user and corresponding mechanism; 
       FIG. 29  is a diagram showing the sectional structure of the operation lever of a second structure example as another embodiment; 
       FIG. 30  is a diagram showing the sectional structure of the operation lever of a third structure example as another embodiment; 
       FIG. 31  is a diagram showing the sectional structure of the operation lever of a fourth structure example as another embodiment; 
       FIG. 32  is a diagram showing the sectional structure of the operation lever of a fifth structure example as another embodiment; 
       FIG. 33  is a diagram showing a planar configuration (state A) of a rear surface (B) in an example of the configuration of a safety mechanism related to a power source system in a power source module of a basic chassis; 
       FIG. 34  is a diagram showing a planar configuration (state A) of a rear surface (D) in an example of the configuration of a safety mechanism related to a power source system in a power source module of an expanded chassis; 
       FIG. 35  is a schematic diagram showing the configuration (state A) in  FIG. 34  seen from above the chassis; 
       FIG. 36  is a diagram showing a planar configuration (state B) of a rear surface (D) in an example of the configuration of a safety mechanism related to a power source system in a power source module of an expanded chassis; 
       FIG. 37  is a schematic diagram showing the configuration (state B) in  FIG. 36  seen from above the chassis; and 
       FIG. 38  is a schematic diagram showing the configuration (state B) in  FIG. 36  seen from a side surface of the chassis. 
   

   DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
   Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted. 
   Features of the Embodiment 
   A disk array system according to an embodiment of the present invention will be described with reference to  FIG. 1  to  FIG. 32 . The main features of the present embodiment are as follows. In a disk array system  500 , for example, in a basic chassis  100 , HDD modules  30 , battery modules  50  and others are installed in a front part  1  of a backboard  20  from a front surface (A), and duplex CTL modules  10  and duplex power source modules  40  containing fan units  42  are installed in a rear part  2  from a rear surface (B). Also, in an expanded chassis  200 , HDD modules  30  are installed in a front part  3  of a backboard  20 B from the front surface (C), and duplex ENC modules  70  and duplex power source modules  80  are installed in a rear part  4  from a rear surface (D). In this structure, as the operating structure for operations of insertion/removal and fixation of a module, an operation lever  5  is used in common for the five types of modules, that is, the CTL module  10 , the power source module  40 , and the battery module  50  of the basic chassis  100  and the ENC module  70  and the power source module  80  of the expanded chassis  200 . 
   &lt;System (1)&gt; 
     FIG. 1  shows a functional block configuration of the information processing system of the disk array system  500 . First, the configuration of the entire system will be described, and then, its characteristic structure will be described. A host system  502  is a high order information processing system such as a PC, a server, and a main frame used by a user. The host system  502  and the disk array system  500  are connected by communication means such as a SAN (Storage Area Network)  501  or a LAN (Local Area Network). 
   The disk array system  500  mainly comprises a basic chassis  100  and an expanded chassis  200 . The basic chassis  100  is provided with both a control function (CTL  110  and the like) and a storage function (HDD  31  group). The expanded chassis  200  is optional and is mainly provided with the storage function (HDD  31  group). 
   A controller (CTL# 1  and # 2 )  110  comprises a CPU  11 , a bridge  12 , a program memory (P memory)  13 , a host I/F (also referred to as a host interface control unit, a channel I/F control unit, and the like)  14 , a data controller (DCTL)  15 , a disk I/F (disk interface control unit)  16 , a cash memory (CM)  17 , a switch (SW)  18 , and others. 
   The CPU  11  executes a program stored in the program memory  13  through the bridge  12 , thereby performing a processing to control the entire system. The DCTL  15  mutually connects each of the units and controls data transmission. The cache memory CM  17  is a shared memory to cash (store) the data in the CTL  110 . The host I/F  14  is a processing unit to which the host system  502  and the like are connected. The disk I/F  16  is a processing unit to which the HDD  31  group is connected via the SW  18 . 
   The SW  18  has a SAS expander (EXP) function and an environment management function. The EXP function is a function such as an access control for the group of HDDs  31  corresponding to the SAS interface. The environment management function includes a function (conventional environment management function) to monitor and detect a trouble, a failure and a state such as connection of resources including a power source (PS), fans, and the HDD  31 , and a temperature management function (cooling management function) including a fan control. 
   The HDD  31  is the SAS HDD (or SATA interface HDD). On the physical memory area provided by the HDD  31  group, a logical volume which is a logical memory area is set. Further, a RAID group by the plurality of HDDs  31  is set, and a RAID control can be executed. The SAS HDDs  31  are connected by “two-path two-port” to the switches SW 18  and SW 19 . 
   The enclosure (ENC# 1  and # 2 )  170  comprises the SW 19  and performs a connection with the CTL  110  and a relay to the ENC  170  when another ENC  170  is connected. The SW  19  has a function similar to that of the SW 18  in the CTL 110  of the basic chassis  100 , and it takes charge of the control in the expanded chassis  200 . The SW 18  of the basic chassis  100  and the SW 19  of the expanded chassis  200  are connected, and the disk I/F  16  can access the target HDDs  31  in the basic chassis  100  and the expanded chassis  200 . 
   As shown by a chain line in the center, the CTL  110 , ENC  170 , HDD  31  group, and others are duplicated, and an access can be made from one side (# 1  and # 2 ) to the other side (# 2  and # 1 ). 
   The data processing in the disk array system  500  is as follows. In response to a data write request (command) from the host system  502 , the CTL  110  temporarily stores the data received from the host I/F  14  in the CM  17  and writes the data in the predetermined logical volume on the HDD  31  group by the disk I/F  16 . Further, in response to the data read request (command) from the host system  502 , the CTL  110  reads the data from the predetermined logical volume on the HDD  31  group by the disk I/F  16  and stores the data temporarily in the CM  17 , and then transmits it to the host system  502  through the host I/F  14 . Since a plurality of host I/Fs  14  and a plurality of disk I/Fs  16  are provided in this configuration, a plurality of data inputs and outputs can be processed in parallel. 
   &lt;System (2)&gt; 
     FIG. 2  shows a system configuration (duplicated parts are omitted) for connecting the modules (shown by m) to the backboards (BB)  20  and  20 B in the basic chassis  100  and the expanded chassis  200  of the disk array system  500 . Through the wirings of the backboards  20  and  20 B, each of the components is mutually connected. In the basic chassis  100 , the HDDs  31  of the plurality of HDD modules  30 , duplex battery modules  50 , and a panel  60  are connected to the front surface of the backboard  20  through the connectors. Further, the duplex CTL modules  10  and the duplex power source (PS) modules  40  are connected to the rear surface of the backboard  20 . In the expanded chassis  200 , the HDDs  31  of the plurality of HDD modules  30  are connected to the front surface of the backboard  20 B through the connectors. Further, the duplex ENC modules  70  and duplex power source modules  80  are connected to the rear surface of the backboard  20 B. 
   The SW 18  of the CTL  110  (the bridge  12  and others are omitted here) and the SW 19  of the ENC  170  have the SAS expander (EXP)  21  corresponding to the EXP function and the environment management unit (K)  22  corresponding to the environment management function. Between the chassis, the connection between the EXPs  21  is made by a communication cable and the like. Incidentally, the configuration in which the environment management unit (K)  22  is located at positions other than the SW 18  and SW 19  is also possible. 
   The EXP  21 , based on a control from the high order disk I/F  16 , controls the data input and output accesses and the path switching and others to the HDD  31  group of each chassis by the SAS interface. 
   The environment management unit (K)  22 , based on a control from the high order (CPU  11  and others), monitors and detects a state of the power source unit ( 41  and the like), the fan unit ( 42  and the like), the HDD  31  and the like installed in the chassis and performs the control of the power source system and the fan control using the fan unit ( 42  and the like) through the backboard  20  and others. 
   The power source module  40  comprises a power source unit  41  and a fan unit  42 . The power source unit  41 , based on an AC input, converts AC into DC by an AC/DC conversion unit  411  and outputs DC power to the backboard  20  from a DC output unit  412 . The DC power is supplied to each component through the circuit of the backboard  20 . The fan unit  42  comprises a plurality of fans  43 . The DC power (driving voltage) is inputted to the fan unit  42  from the power source  41  and others and the fans  43  are rotated. 
   The power source module  80  on the expanded chassis  200  side has basically the same configuration (layout, cooling structure and the like are different) as the power source module  40  on the basic chassis  100  side, and it comprises a power source unit  81 , a fan unit  82  (a plurality of fans  83 ) and others. 
   &lt;Power Source System&gt; 
   The configuration of the power source system of the disk array system  500  will be described with reference to  FIG. 3 . This is the configuration of the power source of two systems corresponding to the duplex structures of the CTL  110 , ENC  170 , and HDD  31  group. The power source unit  41  (# 1  and # 2 ) in each power source module  40  (or  80 ) has a redundant configuration comprising two switching power sources (SWPS)  913  (corresponding to  411 ). This power source unit  41  generates DC outputs (DC# 1  and # 2 ) based on two AC inputs (AC# 1  and # 2 ), respectively, and outputs them to each component such as the corresponding CTL  110  and the like. 
   In each CTL  110 , each processor  911  (CPU  11  and the like) can refer not only to the memory  912  (CM  17  and the like) on its own side (for example, # 1 ) but also to the processor  911  and the memory  912  in the CTL  110  of the other side (for example, # 2 ). The read/write of the data, the control information and others can be mutually performed between the duplex CTLs  110  so that no problem occurs even when one of them is in trouble. 
   The DC output is supplied also to components such as the ENC  170 , HDDs  31 , and the like from the corresponding power source unit in the same manner. When the DC supply is cut off, the DC output is supplied from the battery module  50 . 
   The battery module  50  corresponds to UPS (uninterruptible power source unit), and it contains a plurality of batteries and supplies an emergency power source. When the power supply is stopped due to the power outage and the like, the battery module  50  supplies necessary power to prevent the data loss and the like at the power outage. More specifically, the battery module  50  supplies at least the power required until the data of the memory  912  (CM 17  and the like) is written in the HDD  31  by the processor  911  of the CTL  110  and a premeditated stop is automatically executed and completed. As a result, the data loss at the time of the power outage can be prevented. 
   &lt;Chassis&gt; 
   Next, the external configuration of the entire hardware of the chassis of the disk array system  500  will be described with reference to  FIG. 4  to  FIG. 9  and others. The basic chassis  100  and the expanded chassis  200  have a predetermined size which is mountable on a rack (frame) with a size in conformity to the predetermined standard. The size of the basic chassis  100  is Width: X 1  (about 483 mm), Depth: Y 1  (about 656 mm), and Height: Z 1  (4U, about 172 mm). The size of the expanded chassis  200  is Width: X 1 , Depth: Y 1 , and Height: Z 2  (3U, about 127 mm). For example, the rack (not shown) has a box shape with openings in its front and rear surfaces, and each chassis ( 100  and  200 ) can be mounted up and down therein. 
   The modules to be installed in each of the chassis include various types of modules in the present embodiment, for example, the CTL module  10 , the HDD module  30 , the power source module  40 , the battery module  50 , the ENC module  70 , and the power source module  80 . In the installation of the HDD module  30  to the chassis, the hot plug is enabled. Operations such as insertion/removal and fixation of each module to and from the chassis ( 100  and  200 ) by a person are performed by using an operation lever  5  and the like provided in the module. The operation of the HDD module  30  is performed by using a handle  301  and the like. 
   Each chassis is made of metal in general and has a box shape, and can be disassembled by screws and others. A partition plate and the like which correspond to the area to which each module is installed are provided in the chassis. Further, an outer wall (main body) and the partition plate of the chassis are provided with the structure for the operations of insertion/removal and fixation of the modules, for example, a guide rail (structure of grooves, protrusions, and the like) and a receiving portion of the operation lever  5  (structure for receiving a latch portion  6  and a hook portion  7  of the operation lever  5 ). Further, the partition plate has a function to adjust the flow of the cooling air in addition to the function of fixation, reinforcement, and the like. Incidentally, the duplex two modules have the same configuration and are configured to be attachable to both of the two mounting areas in the chassis. 
   &lt;Basic Chassis&gt; 
   A hardware configuration of the basic chassis  100  will be described with reference to  FIG. 4  and  FIG. 5 .  FIG. 4  is a diagram showing the configuration seen from the side of the opening of the front surface (A) of the basic chassis  100 , and  FIG. 5  is a diagram seen from the side of the opening of the rear surface (B) of the basic chassis  100 . 
   In  FIG. 4 , the basic chassis  100  has openings in the front surface (A) and the rear surface (B) thereof, and the chassis is divided into a front part  1  (front side space) and a rear part  2  (rear side space) by the backboard  20  attached to the position at the midpoint in the chassis as a boundary. 
   In the front surface (A) of the front part  1  of the basic chassis  100 , a plurality of HDD modules  30  can be installed to the upper side area thereof. Further, two battery modules  50  and the panel  60  can be installed to the lower side area thereof. A bezel (door)  91  having an air permeability can be attached to the front surface (A) in a state where each module is installed. 
   In  FIG. 5 , the rear surface (B) of the rear part  2  of the basic chassis  100  has the configuration to which two CTL modules  10  and two power source modules  40  can be installed. The two power source modules  40  are installed in the left and right side areas of the rear surface (B) of the rear part  2 , and the two CTL modules  10  are installed in the areas sandwiched between these power source modules. 
   &lt;Expanded Chassis&gt; 
   A hardware configuration of the expanded chassis  200  will be described with reference to  FIG. 6  and  FIG. 7 .  FIG. 6  shows a configuration of the expanded chassis  200  seen from the side of the opening of the front surface (C), and  FIG. 7  shows a configuration of the expanded chassis  200  seen from the side of the opening of the rear surface (D). 
   In  FIG. 6 , the expanded chassis  200  has the openings in the front surface (C) and the rear surface (D) thereof, and the chassis is divided into a front part  3  (front side space) and a rear part  4  (rear side space) by the backboard  20 B attached to the position at the midpoint in the chassis as a boundary. 
   In the front surface (C) of the rear part  3  of the expanded chassis  200 , the plurality (15 sets) of HDD modules  30  can be installed in a state aligned in a lateral direction. 
   In  FIG. 7 , the rear surface (D) of the rear part  4  of the expanded chassis  200  has the configuration to which two ENC modules  70  and two power source modules  80  can be installed. The duplex ENC modules  70  are disposed side by side in an upper central area of the rear surface (D) of the rear part  4 , and the duplex power source models  80  are disposed side by side in an area below them. 
   &lt;Basic Chassis—Front and Rear Surfaces&gt; 
   Next,  FIG. 8A  shows a configuration of the front surface (A) of the basic chassis  100 . In the front part  1 , a plurality (up to 15 sets in the present embodiment) of HDD modules  30  in an upright position are installed in a relatively wider upper area (A 1 ) in a state aligned in a lateral direction. Two battery modules (# 1  and # 2 )  50  in a horizontal position are installed side by side in a relatively narrower lower area (A 2 ), and the panel  60  is installed adjacent to the battery module, that is, in the lower right corner area of the front surface (A). The panel  60  is a unit to display basic operations and states such as ON and OFF of the disk array system. The boundary between the upper area (A 1 ) and the lower area (A 2 ) is provided with a partition plate. The operation lever  51  is provided at one position of the lower side of the battery module  50 . 
     FIG. 8B  shows a configuration of the rear surface (B) of the basic chassis  100 . In the rear part  2 , the power source modules (# 1  and # 2 )  40  in an upright position are installed in the areas (B 2 ) close to the left and right sides of the rear surface (B). Two CTL modules (# 1  and # 2 )  10  in a horizontal position are installed up and down in the intermediate area (B 1 ) sandwiched between the power source modules. The same two CTL modules  10  are installed upside down relative to each other. The same two power source modules  40  laterally reversed to each other are installed. 
   The partition plate  95  is provided at the boundary between the side surface of the power source module  40  and the side surface of the CTL module  10 . A partition plate is provided at the boundary between the upper and lower two CTL modules  10 . 
   A surface of a host I/F unit  103  corresponding to the host I/F  14  and an area  107  of various types of terminals are provided in a part of the front surface ( 106 ) of the CTL module  10 . Two operation levers  104  are provided at the left and right corners on one side of the front surface ( 106 ) of the CTL module  10 , and the insertion/removal and the fixation of the CTL module  10  by the two operation levers  104  can be performed. 
   Exhaust holes  48  and the like corresponding to the positions of the exhaust ports of fans  43  are provided in the front surface of the power source module  40 . One operation lever  46  is provided close to the center of one side surface of the power source module  40 . 
   &lt;Expanded Chassis—Front and Rear Surfaces&gt; 
     FIG. 9A  shows a configuration of the front surface (C) of the expanded chassis  200 . A plurality (up to 15 sets) of HDD modules  30  are installed into the entire area of the front part  3  in a state aligned in a lateral direction. 
     FIG. 9B  shows a configuration of the rear surface (D) of the expanded chassis  200 . In the rear part  4 , two ENC modules  70  in a horizontal position are installed side by side in an upper central area (D 1 ) of the rear surface (D). Two power source modules  80  in a horizontal position are installed side by side in the lower area (D 2 ). The two ENC modules  70  and the two power source modules  80  are oriented in the same direction. 
   The partition plate  97  is provided at the boundary between the upper ENC module  70  and the lower power source module  80 . A partition plate is provided between the left and right modules. One operation lever  71  is provided at the middle of a lower side of the front surface of the ENC module  70 . 
   The ventilation holes and the like corresponding to the positions of the exhaust ports of fans ( 82 ) are provided in the front surface of the power source module  80 . Two operation levers  86  are provided at the upper left and right sides of the power source module  80 . 
   &lt;Basic Chassis—Horizontal Surface&gt; 
   Next,  FIG. 10  shows a schematic horizontal planar configuration (corresponding to the section of one CTL module  10  seen from above) of the basic chassis  100 . The front part  1  has the HDD modules  30 , and the rear part  2  has the CTL module  10  and the two left and right power source modules  40 . Two fans  43  as a fan unit  42  are provided in a row in a back-and-forth direction on the rear side of the power source module  40 . A lever main body ( 9 ) of the operation lever  104  is disposed on the front surface  106  side of the CTL module  10 . A part (screw fixing portion  8  and hook portion  7 ) of the operation lever  104  is disposed in a recessed portion (notched portion) at the corner of the front surface  106  of the CTL module  10 , and a receiving portion ( 157 ) thereof is provided at a corresponding position of the partition plate  95 . The lever main body ( 9 ) of the operation lever  46  of the power source module  40  is disposed on the side of the chassis rear surface (B) of the partition plate  95  between the CTL module  10  and the power source module  40 , and the corresponding receiving portion ( 156 ) is provided. 
   &lt;Basic Chassis—Vertical Surface&gt; 
     FIG. 11  shows a schematic vertical planar configuration (corresponding to the section of the CTL module  10  seen from the side thereof) of the basic chassis  100 . In the front part  1 , the HDD module  30  is installed on the upper side, and the battery module  50  is installed on the lower side. In the rear part  2 , two CTL modules  10  are installed up and down. The lever main body ( 9 ) of the operation lever  104  of the CTL module  10  is disposed near the upper and lower sides of the chassis rear surface (B). The lever main body ( 9 ) of the operation lever  46  of the power source module  40  (not shown) is disposed near the center in the vertical direction of the chassis rear surface (B). 
   &lt;Basic Chassis—Backboard Surface&gt; 
     FIG. 12  shows the surface (front surface) of the backboard  20  in the basic chassis  100 . The backboard  20  is a circuit board with a roughly flat planar shape and is fixed to a frame part positioned at the middle and slightly close to the front side of the basic chassis  100 . The backboard  20  electrically connects each of the modules through connectors and physically supports them. The fixation of the module mentioned here corresponds to the state in which the connector of the rear surface of the module and the corresponding connector of the backboard  20  are engaged and electrically connected. 
   A group of connectors ( 203 ,  205 , and  206 ) for connecting the HDD module  30 , the battery module  50 , the panel  60 , and the like are provided on the front surface of the backboard  20 . A group of connectors ( 201  and  204 ) for connecting the CTL module  10 , the power source module  40 , and the like are provided on the rear surface of the backboard  20 . Further, wiring patterns for the mutual connection between the connectors and openings (ventilation holes)  220  through which the cooling air is supplied from the front part  1  to the rear part  2  are provided in the backboard  20 . 
   A plurality of connectors (HDD connectors)  203  for the connection of the HDD modules  30  with a longitudinal rectangular shape are disposed on a zone extending in a lateral direction near the center (center zone) of the backboard  20 . Further, connectors (battery connectors)  205  for the connection of the battery modules  50  with a horizontal rectangular shape are disposed below the HDD connectors  203 . Also, a connector (panel connector)  206  for the connection of the panel  60  is disposed near the lower right corner of the backboard  20 . 
   Further, connectors (CTL connectors)  201  to be connected to the CTL modules  10  are disposed near the center of the upper and lower sides on the rear surface side of the backboard  20 , while interposing the area of the HDD connector  203  therebetween. That is, on the upper side, the CTL connector  201  for the connection of the module ( 10 ) of a first CTL (# 1 ) with a lateral rectangular shape is disposed. On the lower side, the CTL connector  201  for the connection of the module ( 10 ) of a second CTL (# 2 ) is similarly disposed. Further, connectors (power source connectors)  204  for the connection of each power source module  40  with a longitudinal rectangular shape are disposed near the center of the left and right sides of the backboard  20 . 
   &lt;HDD Module&gt; 
   Next,  FIG. 13A  and  FIG. 13B  show the HDD module  30  (also referred to as canister module). The HDD  31  is stored in the HDD module  30 , and a connector  32  to be connected to the connector  203  on the backboard  20  is provided on the rear surface of the HDD module  30 . A handle  301  is provided on the front surface of the HDD module  30 , and the operation of insertion/removal and fixation of the HDD module  30  can be performed by this handle. The HDD module  30  has a uniform external appearance by the design of the handle  301  and the like. The HDD  31  of the HDD module  30  installable in the present embodiment is either the Serial Attached SCSI HDD (SAS-HDD)  31  shown in  FIG. 13A  or the Serial ATA (SATA) interface HDD (SATA-HDD)  35  shown in  FIG. 13B . 
   In  FIG. 13A , in consideration of the position of the connector  32  of the SAS-HDD  31  and the installing position of the HDD module  30 , the connector position of each of other modules, the module installing position, and shape are designed. Between the duplex CTL  110  (disk I/F  16 ) and the SAS-HDD  31 , the data input/output processing is performed by the “two-port and two-path (2P)” according to the SAS interface. The SAS-HDD  31  side has two ports (2P). 
   In  FIG. 13B , when the HDD module  30  of the SATA-HDD  35  is to be installed, a path control board (I/F conversion board)  37  is interposed and connected between the connector  36  of the SATA-HDD  35  and the connector ( 203 ) of the backboard  20  so as to match with the position of the connector  32  of the SAS-HDD  31 . More specifically, the connector  32  of the SAS-HDD  31  and the corresponding connector of the path control board  37  are connected, and the connector  38  of the path control board  37  and the corresponding connector ( 203 ) of the backboard  20  are connected. The SATA-HDD  35  has one port (1P). In the case of the connection of the SATA-HDD  35 , the I/F conversion is performed by the SATA and the SAS by the control board  37  having the two ports. 
   &lt;Power Source Module&gt; 
   In  FIG. 14A  and  FIG. 14B , the power source module  40  has an integrated module configuration including the power source unit  41  and the fan unit  42 , thereby reducing the size of the chassis.  FIG. 14A  shows a state in which one power source module  40  is installed between the outer wall  99  of the basic chassis  100  and the partition plate  95  in a horizontal plane.  FIG. 14B  schematically shows the state in a vertical plane (side surface). 
   The power source unit  41  comprises a substrate  44 , and a connector  45  to be connected with the corresponding connector  204  of the backboard  20  is provided on the rear surface side of the power source module  40 . The operation lever  46  is disposed on the side of the chassis rear surface (B) of the partition plate  95  and receiving portions ( 156 ,  157 ) corresponding thereto are provided in the partition plate. The operation lever  46  is disposed outside the external shape (box-like shape) of the power source module  40  (formed as a projected portion). 
   The fan unit  42  has a redundant configuration to cool the inside of the basic chassis  100  by the operation of a plurality of fans (air blowers)  43 . In the present embodiment, the fan unit  42  is similarly provided with two fans  43  each in the upper and lower areas corresponding to the upper and lower two CTL modules  10 , and further, it is provided with two (duplex) fans  43  aligned in a back-and-forth direction (in tandem). In this configuration, total of four fans  43  are provided in one power source module  40 . As the fan  43 , for example, a fan such as an axial-flow fan is used. 
   By a blade rotational motion by a DC power supply, each fan  43  takes air from an air-intake port facing the front surface (A) of the chassis and exhausts the air from the exhaust port facing the rear surface (B) of the chassis. By the operation of the fan  43 , the cooling air is taken in from the air intake port, and then exhausted to the outside of the basic chassis  100  from the exhaust port in the back and the exhaust hole  48  of the power source module  40 . 
   &lt;CTL Module&gt; 
     FIG. 15  shows a structure of the CTL module  10  in a disassembled state. After storing and connecting component parts such as a CTL substrate (control package)  120 , a host I/F unit  103 , and the like in a main body  101  of the CTL module  10 , a top cover  102  serving as the upper surface is attached by screws and the like. 
   The CTL substrate  120  is attached to the inner bottom surface of the main body  101 . The CTL substrate  120  generally has a plate-like shape formed of a substrate  113 . A connector (BB connecting connector)  111  to be connected to the backboard  20  is provided on one side of the CTL substrate  120 . Components such as an IC are mounted on the substrate  113 . The main body  101  and the top cover  102  are package mainly formed of sheet metal constitute most of the external shape of the CTL module  10 . The front surface  106  (the rear surface (B) side of the basic chassis  100 ) of the may body  101  has a notched area corresponding to the attachment of the host I/F unit  103 . The host I/F unit  103  includes a substrate, a front panel, terminals and others. The connector  111  and the like of the CTL substrate  120  are exposed on the rear surface side of the main body  101 . 
   Further, various terminals, display elements, and the like are mounted in a part of the area of the front surface  106  of the CTL module  10 , particularly in an area  107  near the center of the lower side thereof. In this area  107 , for example, a display LED, LAN terminal, backend system terminal, remote adaptor terminal, UPS terminal and the like are mounted. 
   Further, on the left and right sides of this area  107 , that is, at the bottom left and right corners of the front surface  106 , the operation levers  104  in a horizontal position are provided. In the mechanism of the operation lever  104 , for example, the CTL module  10  is fixed and released to and from the chassis by the operation of rotating a rod-like lever main body ( 9 ) on a screw fixing portion  8  (fulcrum point) at the corner of the CTL module  10 , that is, by the operation of moving up or down the lever main body ( 9 ) on the front surface  106  of the CTL module  10 . When fixing the module, the lever main body ( 9 ) is put down so as to be in parallel with the front surface  106 . By this means, its one end (side surface side) is hooked on the structure (receiving portion) on the side of the partition plate  95  of the chassis, and the other side (inner side) is latched on the structure (receiving portion  156 ) on the side of the front surface  106  of the CTL module  10 . 
   &lt;Example of Conventional Technology&gt; 
   Next, for comparison purpose, a configuration (chassis, module and operating structure) in the disk array system of the conventional technology (background technology) of the present embodiment will be briefly described below. In this conventional technology, in the basic chassis, modules such as the HDD group, the battery, and the like are installed in the front part, that is, on the front surface side from the backboard. Also, three types of modules such the CTL, power source, and fans and duplicated modules thereof, that is, a total of six modules are installed in the rear part, that is, on the rear surface side from the backboard. In the rear part, two CTL modules are adjacently disposed up and down in the upper area, and two power source modules are adjacently disposed side by side in the lower area. Two fan modules are disposed on both left and right sides of these modules. That is, in this configuration, power source module and fan module are separated. The HDD is, for example, a HDD of a fiber channel I/F. Further, in the expanded chassis, the modules of the HDD group are installed in the front part, that is, on the front surface side from the backboard. Two types of modules of the ENC and the power source and duplicated modules thereof, that is, a total of four modules are installed in the rear part, that is, on the rear surface side from the backboard. In the rear part, two ENC modules are adjacently disposed side by side in the upper area, and two power source modules are adjacently disposed side by side in the lower area. 
   The operating structures of these modules are different in each module (for example, CTL module, power source module) due to a difference in the mounting structure of the system chassis and modules. For example, some modules are connected directly, some modules are mounted by fixing its lever with screws using a screw driver, and some modules are mounted with a locking bar. 
   &lt;Design of Basic Chassis and Module&gt; 
   The outline of the design for the basic structure of the basic chassis  100  and the layout of each module in the chassis will be shown in the following (1) to (4). Basically, based on the mounting details of the modules, required specifications, and the like, the shape, size, layout, and the like of the module are designed considering the prevention of the interference between the connectors in the backboard  20  and the cooling structure in the chassis and the size reduction thereof (size standard and the like). With respect to the connector interference, the design is made so that the positions of the connectors to connect each module do not overlap one upon another and they are not located too close in the front and rear surfaces of the backboard  20 . 
   (1) The layout of the HDD modules  30  is determined. Since the specification basically requires the mounting of the SAS-HDD  31 , the position of the connector  32  on the side of the HDD  31  of the HDD module  30  and the position of the corresponding connector  203  on the side of the backboard  20  are determined. Specifically, the positions of the connectors ( 32  and  203 ) are located in the center zone of the backboard  20  as shown in  FIG. 12  and  FIG. 13 . Further, in the front part  1 , the battery module  50  and the like are disposed below the HDD module  30 , and the configuration of the front part  1  is thus roughly determined. Also when the SATA-HDD  35  is installed, because of the interposition of the path control board  37 , the chassis has approximately the same configuration as the case of SAS-HDD  31  in its entirety. By the change in the specification from the conventional configuration, the position of the connector  32  of the SAS-HDD  31  for the backboard  20  of the present configuration differs from the conventional position of the connector of the HDD of the fiber channel I/F for the backboard (moved from upper area to the center zone). 
   (2) The layout of the CTL module  10  is determined. The position of a connector  111  of the CTL module  10  and the position of the corresponding connector  201  on the backboard  20  are determined so as to prevent the connector interference in the backboard  20 , in particular, to prevent the overlap with the position of the connector  32  of the HDD module  30  of the item (1). Specifically, the positions of the connectors ( 111  and  201 ) are located at the positions near the upper and lower sides of the backboard  20  as shown in  FIG. 12  and  FIG. 13 . In the conventional configuration, the two power source modules are disposed below the two CTL modules (# 1  and # 2 ), and the connector of one CTL module (# 2 ) is disposed near the center of the backboard. In the present configuration, in the rear part  2 , the conventional two power source modules are moved to the left and right side areas (power source module  40 ), and two CTL modules ( 10 ) only are adjacently disposed up and down in the area between the power source modules. By this means, the position of the connector of one (lower side) CTL module (# 2 ) is moved further downward than the conventional position. 
   (3) The layout of the power source module  40  is determined. According to the item (2), though the power source modules  40  are disposed in the left and right side areas (B 2 ) of the chassis, since the fan modules exist in these areas in the conventional configuration, the power source modules  40  are integrated with the fan modules. More specifically, this power source module  40  is a combination type containing the power source unit  41  and the fan unit  42 . Further, the positions of the connector  45  of the rear surface of the power source module  40  and the corresponding connector  204  on the backboard  20  are determined so as to prevent the connector interference. Specifically, the positions of the connectors ( 45  and  204 ) with a longitudinal rectangular shape are located near the left and right sides of the backboard  20  as shown in  FIG. 12 . The connectors of the power source module of the conventional configuration are disposed near the lower side of the backboard. In the present configuration, however, these connectors are unified with connectors of the left and right fan modules and are moved to the positions near the left and right sides of the backboard  20 . In this manner, the configuration of the rear part  2  is roughly determined. 
   (4) Next, the structure of the flow path of the cooling air from the front surface (A) of the front part  1  to the rear surface (B) of the rear part  2  of the basic chassis  100  through the backboard  20  is considered and designed. The layout and size distribution of the module mounting area in the chassis, the layout of the partition plate and ventilation hole, the layout, area, and the like of the opening hole  220  of the backboard  20  are considered and designed. 
   &lt;Design of Operation Lever&gt; 
   The configuration of the operation lever  5  will be described based on the configuration of the disk array system  500  described above. The design of the common operation lever  5  in this disk array system  500  is outlined as follows. 
   (1) The modules to which the operation lever  5  is provided include five types of modules, that is, the CTL module  10 , the power source module  40  and the battery module  50  of the basic chassis  100  and the ENC module  70  and the power source module  80  of the expanded chassis  200 . The plurality of HDD modules  30  are excluded from the object for consideration because there occurs no problem in operability if a structure such as its own handle  301  is provided. As the operation lever  5 , the two operation levers  104  of the CTL module  10 , the operation lever  46  of the power source module  40 , the operation lever  51  of the battery module  50 , the operation lever  71  of the ENC module  70 , and the two operation levers  86  of the power source module  80  are provided. 
   (2) If the structure of the chassis and module is considered in the design of the common operation lever  5  for the modules, the force necessary for the operations of insertion/removal and fixation of the modules (connector coupling) is largest in the CTL module  10  among the various modules. Accordingly, the structure of the operation lever  104  to be provided to the modules is determined based on the CTL module  10  of the basic chassis. Then, the structure and method of the operation lever  104  are applied to other modules ( 40 ,  50 ,  70 , and  80 ) in common, that is, all the object modules are provided with the common operation lever  5 . 
   In the CTL module  10 , the CTL substrate  120  is mounted and its rear surface is connected to the backboard  20  through a connector. That is, the connector  111  on the rear surface side of the CTL module  10  is coupled with the corresponding connector  201  on the backboard  20 . The force necessary for the operation (operation force) of the CTL module  10  is estimated from the force necessary for the connector connection (connector coupling force). Accordingly, the operation lever  104  to be provided to the CTL module  10  is designed. In one CTL module  10 , for example, two same operation levers  104  are required because a relatively large operation force is applied. 
   (3) The detailed configuration of the operation levers  5  to be provided to various object modules ( 10 ,  40 ,  50 ,  70 , and  80 ) including the operation lever  104  provided to the CTL module is determined. Since the installation area, connector coupling force and detailed requirement for mounting in the chassis differ depending on each module, the difference in the configuration of the operation levers  5  for each module, for example, the number of arranged levers, position and mounting method thereof is determined in detail in accordance with the differences. As for the number of the operation levers to be arranged, an operation lever is arranged if the necessary operation force is satisfied or two levers are arranged if the operation force is insufficient. The arrangement position is a position exposed on a side of an opening of the chassis (front surface or rear surface) in consideration of the positions of the connectors for the connection to the backboards  20  and  20 B. As for the mounting method of the operation lever, the operation lever is disposed and mounted inside (in a recessed portion) or outside (on a projected portion) the module area which is substantially box-shaped in its external shape, and alternatively, the receiving portion for the component of the operation lever  5  is provided in the form of an internal mounting portion (recessed portion) or an external mounting portion (projected portion) in an area (wall or others) of the chassis or the module. 
   &lt;Basic Structure of Operation Lever&gt; 
     FIG. 16  shows the basic structure of the operation lever  5 . The operation lever  5  is a latch-type lever having a mechanism using the principle of leverage and constituted of a lever main body  9 , a screw fixing portion (rotary shaft portion)  8 , a latch portion (fixed latch portion)  6 , a hook portion  7 , and others. One or more operation levers  5  are attached at each predetermined position of a module in consideration of a force (operation force) necessary for the operation of the module. The lever main body  9  can be moved down or up with respect to the module surface by the rotary shaft portion  8 . The latch portion  6  is fixed to the structure of the receiving portion on the chassis side or the module side by the latch action when the module is fixed. The hook portion  7  is fixed to the structure of the receiving portion on the chassis side when the module is fixed. 
   &lt;Design of Operation Lever Arrangement&gt; 
   The basis of the design of the arrangement (mounting position) of the operation lever  5  with respect to the module will be described below with reference to  FIG. 17 . The basic concept for determining a preferred arrangement of the operation lever  5  in the module will be described. The arrangement position of the operation lever  5  to the module is determined based on a balance of the connector connection force between the module and the backboards  20  and  20 B. More specifically, in the operation for insertion/removal and fixation of the module by the operation lever  5 , it is required that the lever can bear a sufficient force.  FIG. 17  shows an example of the position of the connector  191  to be connected to the backboard  20 / 20 B in an object module  190  substantially rectangular in its external shape (lower side of the rear surface of the module  190 ), and it also shows an example of the positions (points b, c, e, f, etc.) at which the operation lever  5  is to be disposed and the operation lever arrangement area (areas  192  to  195 ). The respective areas  192  to  195  indicate a range in which the object areas for arrangement and installation of the operation lever  5  can be contained. The detailed mounting position in the areas  192  to  195  is determined considering the mounting structure nearby. 
   More specifically, the mounting position is determined as follows. Basically, it is determined considering the operation force based on the connector coupling force with the backboards  20  and  20 B. Arrows indicate the direction in which an operation force works when the module  190  is inserted or removed. As an ideal position, the lever is disposed at a symmetrical position with respect to the center position of the connector  191  (for example, in case where the connector  191  is located on the lower side of the rear surface) to be connected to the backboards  20  and  20 B of the rear surface of the object module  190 . That is, on the surface seen from above where the connector  191  is disposed (lower surface of the module  190 ), the ideal position is the point b defined by an extension line (a-b) from a center position (point a) of the connector  191  on the rear surface to its corresponding position (point b) on the front surface  199  of the module  190  on an opposite side. It is ideal to dispose the hook portion  7  (point of action) of the operation lever  5  at this position (point b). When one operation lever  5  is disposed in the area  192  of this position (point b) and the condition for the operation force is satisfied, the structure is preferable. 
   In addition to the description above, the area in which the operation lever  5  is to be disposed is required not to interfere with an area of any mounting components of the module  190  and the chassis corresponding to the module  190 . The structure in which the operation lever is arranged at the ideal position (point b, area  192 ) is difficult in some cases because of detailed requirement of the installation. For example, when an area in which a necessary component is mounted is present near the point b and the mounting space of the operation lever  5  cannot be secured, it is difficult to use the structure described above. In such a case, the operation lever is disposed at a position shifted from the ideal position to its surrounding. 
   For example, the operation levers  5  are disposed at symmetrical positions (area  193  of the point e, area  194  of the point f) on the right and left sides of the ideal position (point b) on the front surface  199  of the module  190 , and a single operating function is borne by the two operation levers  5 . Unless the necessary operation force can be given by a single operation lever  5 , two or more operation levers  5  are disposed at symmetrical positions such as the right and left positions as described above. Note that it is inappropriate to arrange or mount only one of these two operation levers  5  in view of the balance of force. 
   Further, a next preferable position to the ideal position (point b) is not limited to the right and left positions but may be at a position on an extension line (b-c) extending in a vertical direction from the point b on the front surface  199 , in particular, it may be an area  195  of the point c. In other words, it may be a position (point c) existing on a section including the center position (point a) of the connector  191  in the direction of the side surface of the module (a-b-c-d) and farther from the center point (point a) of the connector  191  on the rear surface than the ideal position (point b). 
   Further, the detailed arrangement and mounting structure of the operation levers  5  are determined considering the detailed structure of the module  190  and the structure of the chassis adjacent to the module. For example, the direction of the operation lever  5  (vertical and horizontal arrangement, arrangement on the front surface of the module or arrangement on the side surface of the module) is determined. Further, for example, the operation lever is disposed and mounted in a recessed portion (internal part) or on a projected portion (external part) of an area of the module  190 . Also, the internal arrangement in the case where the notched portion (recessed portion) exists in the area of the module  190  or the external arrangement in the case where such notched portion does not exist can be selected. The chassis has the receiving portion ( 156 ,  157 ) which is a structure to receive a part (latch portion  6  or hook portion  7 ) of the operation lever  5 . As such a structure, for example, there are structures of the recessed portion (internal part) and projected portion (external part). As the structure of the receiving portion ( 156 ) of the latch portion  6 , for example, provision of a hole in the outside wall of the module or attachment of a recessed component is available. As the structure of the recessed portion (internal part) of the receiving portion ( 157 ) of the hook portion  7 , for example, provision of a hole in the plate metal (outside wall or partition plate) of the chassis or attachment of a recessed component is available. Further, as the structure of the projected portion (external part), attachment of a separate component (external attachment metal with screws) to the chassis or formation thereof directly to the chassis (plate metal) is available. 
   &lt;Operation Force&gt; 
   The operation force of the operation lever  5  will be described with reference to  FIG. 16 . An operation force necessary for the operation lever  5  is estimated and calculated for each module based on the arrangement position, number, and coupling force between the connectors (connector coupling force) in the module. The connector coupling force can be calculated from the capacity of power source, the number of signal lines and others. The operation force differs depending on each module in accordance with the differences in plural types of the modules. In the chassis and module structure of this disk array system  500 , the operation force is largest in the CTL module  10  and becomes smaller in the order of the power source module  80  of the expanded chassis  200 , the ENC module  70 , the power source module  40  of the basic chassis  100 , and the battery module  50 . The condition for forming a plurality of operation levers in plural types of the modules is that one operation lever (one of two operation levers) of the CTL module  10  covers the operation force of one operation lever in other modules (the former is greater than the latter). By satisfying this condition, the operation lever can be used in common as a plurality of operation levers in the plural types of modules based on the operation lever  104  of the CTL module  10 . 
   An example of the estimation calculation is shown below. A lever ratio is calculated from the operation force of the operation lever  5  and the connector coupling force (load on the operation lever  5 ) and necessary external dimensions of the operation lever  5  (length of the lever main body  9  and others) are measured, thereby determining the specifications. A denotes a length from a fulcrum point (rotary shaft portion  8 ) to the tip (power point) of the lever main body  9 . B denotes a length from the fulcrum point (rotary shaft portion  8 ) to the tip (action point) of the hook portion  7 . W, denotes a force applied to the tip (power point) of the lever main body  9 . W 2  denotes a force applied to the tip (action point) of the hook portion  7 . The lever ratio is a ratio of length between A and B for obtaining a necessary operation force around the fulcrum point (rotary shaft portion  8 ). W 1 :W 2  is equal to A:B. If A is increased relative to B, the necessary operation force is decreased due to the principle of leverage. The stroke (ST) is a predetermined movable length which can be obtained when the operation lever  5  is rotated around the fulcrum point (rotary shaft portion  8 ) of the operation lever  5  in the insertion or removal of the module. ST is, for example, 14 mm. 
   An example of the estimation of the connector coupling force (unit: [N]) of each module in the aforementioned structure of the disk array system  500  is shown below. The coupling force mentioned here refers to the maximum coupling force necessary for the insertion or removal of the module. In each module of the basic chassis  100 , the coupling force is 250N for the CTL module  10 , 110N for the power source module  40 , 35N for the battery module  50 . In each module of the expanded chassis  200 , the coupling force is 125N for the ENC module  70  and 110N for the power source module  80 . As evident from above, the CTL module  10  of the basic chassis  100  has the largest coupling force in all the modules. Thus, the common operation lever  5  is designed (calculated) based on the CTL module  10 . 
   The design of the operation lever  5  is made in the following manner. The maximum connector coupling force is 250[N]. The specification of the lever operation force is 39.2[N] (≈4[kgf] or less: design target value). Since the necessary operation force cannot be obtained with one operation lever  5  for the CTL module  10 , the design is made so as to provide two operation levers  5 . Here, “maximum connector coupling force”÷“the number of operation levers”=“load applied to a single operation lever”, that is, 250÷2=125[N]. 
   The modules ( 40 ,  50 ,  70 ,  80 ) other than the CTL module  10  can be operated with a load ( 125 N) corresponding to that of a single operation lever  5 . Here, “load applied to one operation lever”÷“specification of operation force of the operation lever”=125÷39.2≈3.2. Thus, the specification of the lever ratio (A:B) is set to 3.2. 
   &lt;CTL Module—Arrangement of Operation Lever&gt; 
   Next, the design of arrangement of the operation levers  104  in the CTL module  10  of the basic chassis  100  will be described with reference to  FIG. 18 .  FIG. 18  shows the case where the module is installed on the lower side of the rear surface (B) of the rear part  2  (# 2 ). The substrate  113  of the CTL substrate  120  is disposed on the lower surface in the CTL module  10 , and the connector (BB connecting connector)  111  of the CTL substrate  120  is disposed on the lower side of the rear surface. 
   Similar to  FIG. 17 , the ideal position for the arrangement of the operation lever  104  is a position (point b) near the center of the front surface  106  on the center line (a-b) of the connector  111  on the rear surface. However, the area near this point b is inappropriate for the arrangement of the operation lever  104  due to interference in view of the mounting specification of the CTL module  10  because this area is to be an area  107  where a terminal or the like is mounted. Therefore, as a position second best to this point b, the position on a line (e-f) in the right and left direction or that on a line (b-c) in the vertical direction is considered. Since the area  107  for the terminal or a host I/F mounting area  108  exists on the line (b-c) in the vertical direction, the two operation levers  104  are disposed on the line (e-f) in the right and left direction, in particular, symmetrically in an area  116  near the right bottom corner (point e) and in an area  117  near the left bottom corner (point f). 
   &lt;Power Source Module (Basic Chassis)—Arrangement of Operation Lever&gt; 
   The design of arrangement of the operation lever  46  to the power source module  40  of the basic chassis  100  will be described with reference to  FIG. 19 .  FIG. 19  shows the case where the module is installed in the left side area of the rear surface (B) in the rear part  2  (# 1 ). A substrate  403  of the power source unit  41  is disposed on the side surface of the chassis (outside wall  99 ) in the power source module  40 , and a corresponding connector  401  is provided on the rear surface. Further, an area  404  in which the fans  43  of the fan unit  42  are mounted up and down is provided near the front surface at the back of the power source unit  41 . 
   The preferred position for the arrangement of the operation lever  46  is as follows. The ideal position for the operation lever is on an extension line (a-b) from the center point a of the connector  401  toward the front surface side, in particular, near the point b on the front surface. However, arrangement of the operation lever  46  on this extension line (a-b) is inappropriate due to interference in view of the mounting specification of the power source module  40  because the substrate  403  of the power source unit  41  and the fan  43  exist on the extension line (a-b) and an inlet or LED is mounted in the area  406  near the point b and near the center of the front surface (between the exhaust holes  48 ). Therefore, as a position second best to the ideal point b, an area near a point c on an extension line (b-c) in the direction from the side surface (left side face) of the point b to its opposite side surface (right side surface) can be considered. The operation lever  46  is disposed in an upright position on the side surface (right side surface) near the point c so as to correspond to the direction of the connector  401 . 
   &lt;Battery Module—Arrangement of Operation Lever&gt; 
   The design of arrangement of the operation lever  51  to the battery module  50  of the basic chassis  100  will be described with reference to  FIG. 20 . A substrate  53  of the battery module  50  is disposed in a part of the upper surface (right side) of the battery module  50 , and a corresponding connector  52  is disposed in a part of the upper side of the rear surface (right side). Further, an area  56  in which the battery is disposed is provided on the left side in the battery module  50 . 
   The preferred position for the arrangement of the  5  operation lever  51  is as follows. A point b on an extension line (a-b) from the center point a of the connector  52  to the front surface is an ideal position. However, since the substrate  53  exists on this extension line (a-b), the operation lever  51  cannot be disposed thereon in view of the mounting specification of the module. Therefore, as a position second best to the ideal point b, the operation lever  51  is disposed on an extension line (b-c) downwardly extending from the point b to the lower surface, in particular, in an area  55  near the point c. 
   &lt;ENC Module (Expanded Chassis)—Arrangement of Operation Lever&gt; 
   The design of arrangement of the operation lever  71  to the ENC module  70  of the expanded chassis  200  will be described with reference to  FIG. 21 . A substrate  73  of the ENC  170  is disposed on the upper surface of the ENC module  70 , and a corresponding connector  72  is disposed on the upper side of the rear surface. 
   The preferred position for arrangement of the operation lever  71  is described below. A point b on an extension line (a-b) extending from the center point a of the connector  72  to the front surface is an ideal position. However, the operation lever  71  cannot be disposed on this extension line (a-b) in view of the detailed mounting specification of the module because the substrate  73  of the ENC  170  exists on this extension line (a-b). Therefore, as s position second best to the point b of the ideal position, a position on an extension line (b-c) extending downwardly from the point b to the lower surface can be considered. An area  76  on the upper side of the front surface including the line (b-c) is inappropriate for the arrangement of the operation lever  71  due to interference because a path input/output connector or LED is mounted in this area. Accordingly, the operation lever  71  is disposed in an area  75  near the point c. 
   &lt;Power Source Module (Expanded Chassis)—Arrangement of Operation Lever&gt; 
   The design of arrangement of the operation lever  71  to the power source module  80  of the expanded chassis  200  will be described with reference to  FIG. 22 . A substrate  803  of the power source unit  81  is provided on the lower surface in the power source module  80 , and a corresponding connector  801  is provided on the lower side of the rear surface. Further, areas  804  in which the fans  83  are to be mounted side by side are provided in the front surface of the power source module  80 . 
   The preferred position for the arrangement of the operation lever  86  is as follows. A point b on an extension line (a-b) extending from the center point a of the connector  801  to the front surface is an ideal position. However, the operation lever  86  cannot be disposed on this extension line (a-b) in view of the detailed mounting specification of the module because the substrate  803  of the power source unit  81  or an incorporated fan  83  exists on the extension line (a-b). Therefore, as a position second best to the ideal point b, a position on an extension line (b-c) extending upwardly from the point b to the upper surface and an area near the point c can be considered. The area on the extension line (b-c) is inappropriate for the arrangement of the operation lever  86  due to interference because an LED or the like is mounted in this area, and the right and left sides of the front surface are also inappropriate because the fan  83  and an inlet are disposed in these areas. Further, the specification (condition) can be satisfied by disposing one operation lever  86  near the point c if the aforementioned necessary operation force is considered. In this example, however, the two operation levers  86  are disposed symmetrically on the right and left of the point c, that is, in an area  806  near a point e at a corner of the front surface and an area  807  near a point f in consideration of the installation of other module (ENC module  70 ). 
   &lt;CTL Module—Arrangement of Operation Lever&gt; 
   Also, in the mounting example of the operation lever  104  to the CTL module  10  shown in  FIG. 18  and  FIG. 23A , the screw fixing portions  8  of the operation levers  104  are attached in the notched portions at the right and left corners of the front surface  106  of the CTL module  10 . The lever main body  9  is disposed outside the external shape (box-like shape) of the CTL module  10 . The lever main body  9  is provided horizontally so that it is opened (stood) from the inside of the module front surface  106  in the direction toward the side surface of the module. The receiving portion  156  of the latch portion  6  is provided at a predetermined position corresponding to the length of the lever main body  9  inside the right and left corners of the module front surface  106 . The receiving portion for the hook portion  7  is provided as a recessed portion in the partition plate  95  adjacent to the side surface of the module. 
   &lt;Power Source Module (Basic Chassis)—Arrangement of Operation Lever&gt; 
   Also, in the mounting example of the operation lever  46  to the power source module  40  shown in  FIG. 19  and  FIG. 23A , since the fan  43  or the like exists inside the external shape (box-like shape) of the power source module  40 , the screw fixing portion  8  and the lever main body  9  of the operation lever  46  are disposed in an area outside thereof. The receiving portion  156  of the latch portion  6  and the receiving portion  157  of the hook portion  7  are provided as recessed portions in the partition plate  95  adjacent to its side surface (right side surface). Further, the two operation levers  5  can be disposed near the corners (points e and f) in consideration of a margin for the force on the premise that they do not interfere with any adjacent module. 
   &lt;Battery Module—Arrangement of Operation Lever&gt; 
   Also, in the mounting example of the operation lever  51  to the battery module  50  shown in  FIG. 20  and  FIG. 23B , the lower surface of the module  50  corresponds to the outside wall (lower surface) of the basic chassis  100  in an area near the point c on the lower side of the front surface in  FIG. 20 , and no operation lever  51  is disposed on this side. Instead, the screw fixing portion  8  of the operation lever  51  and the receiving portion are disposed on the internal side of the external shape (box-like shape) of the battery module  50 . For this reason, the external shape of the battery module  50  has a notched portion (recessed portion)  54  in its lower surface side. The notched portion  54  is provided so that it penetrates from the front surface to the rear surface in the area near the line (c-d) of the lower surface corresponding to the point c in consideration of the operation for insertion or removal of the battery module  50 . The screw fixing portion  8  of the operation lever  51  is attached to an end portion of the notched portion  54 , and correspondingly, the receiving portion  156  of the latch portion  6  is provided at a predetermined position inside the battery module  50 . Further, the receiving portion  157  of the hook portion  7  is provided as a projected portion on the outside wall side of the basic chassis  100  in the space of the notched portion  54 . 
   &lt;ENC Module (Expanded Chassis)—Arrangement of Operation Lever&gt; 
   Also, in the mounting example of the operation lever  71  to the ENC module  70  shown in  FIG. 21  and  FIG. 24 , the lower surface of the module  70  corresponds to the partition plate  97  of the expanded chassis  200  in an area near the point c on the lower side of the front surface in  FIG. 21 , and no operation lever  71  is disposed on this side (operation lever  86  of power source module  80  is provided). Instead, the screw fixing portion  8  of the operation lever  51  and the receiving portion are disposed on the internal side of the external shape (box-like shape) of the ENC module  70 . For this reason, the external shape of the ENC module  70  has a notched portion (recessed portion)  74  in its lower surface side. The notched portion  74  is provided so that it penetrates from the front surface to the rear surface in the area near the center line (c-d) of the lower surface in consideration of the operation for insertion or removal of the ENC module  70 . The screw fixing portion  8  of the operation lever  71  is attached to an end portion of the notched portion  74 , and correspondingly, the receiving portion  156  of the latch portion  6  is provided at a predetermined position inside the ENC module  70 . Further, the receiving portion  157  of the hook portion  7  is provided as a projected portion on the side of the partition plate  97  of the expanded chassis  200  in the space of the notched portion  74 . 
   &lt;Power Source Module (Expanded Chassis)—Arrangement of Operation Lever&gt; 
   Also, in the mounting example of the operation lever  86  to the power source module  80  shown in  FIG. 22  and  FIG. 24 , the screw fixing portion  8  and the lever main body  9  are disposed in an area outside the power source module  80 , that is, on the side of the partition plate  97  of the expanded chassis  200  instead of inside the external shape of the power source module  80 . Further, the receiving portion  156  of the latch portion  6  and the receiving portion  157  of the hook portion  7  are provided as recessed portions on the side of the partition plate  97 . 
   In each of the above-described structures of the modules except the CTL module  10 , the operation lever  5  is disposed not on the same plane as the connector but diagonally. Further, in the power source module  40  and the ENC module  70 , the operation lever  5  is disposed at a central position of a side of the front surface because it can be disposed in such a manner. Further, the case of the internal mounting structure (using the recessed portion) to the external shape of the module is effective when no component interfering with the module exists at an arrangement object position of the operation lever  5 , and accordingly, the module is reduced in size. Further, the case of the external mounting structure (using the projected portion) to the external shape of the module is effective when no interfering component (structure) of the chassis exists at an arrangement object position of the operation lever  5 , and therefore, the module can have a box-like external shape. The detail of these mounting structures can be appropriately selected considering the relationship among plural modules. 
   &lt;Structure of Operation Lever (1)&gt; 
   Next,  FIG. 25A  to  FIG. 25D  show the detailed structure (first structure example) of the operation lever  5 .  FIG. 25A  shows a structure thereof seen from the front side,  FIG. 25B  shows the appearance of the side surface,  FIG. 25C  shows a sectional structure (section along the line A-A of  FIG. 25A ) thereof seen from the side,  FIG. 25D  shows a tip side of the operation lever  5 , indicating the latch portion  6  seen from above. The operation lever  5  has the latch portion  6  which is a movable portion at one end, that is, at a tip of the lever main body  9  having a predetermined length from the rotary shaft portion  8  and has the hook portion  7  at a position near the rotary shaft portion  8  at the other end thereof. The lever main body  9  and the latch portion  6  are made of, for example, plastic. 
   In  FIG. 25A , the tip (a portion to be pressed by a user) of the latch portion  6  projects from an end of the lever main body  9  as also shown in  FIG. 25D . A hole portion  153  is provided near the tip of the lever main body  9  so as to correspond to the arrangement of the latch portion  6 . A part of the latch portion  6  in the lever main body  9 , in particular, a fastening portion  162  of the latch portion  6  is seen in the hole portion  153 . The hook portion  7  is seen at the other end of the lever main body  9 . The operation lever  5  incorporates a spring portion  151  made of metal between the lever main body  9  and the latch portion  6  for the latch action of the latch portion  6 . The lever main body  9  incorporates the spring portion  151  in contact with the latch portion  6 . Further, the latch portion  6  is incorporated in a state in contact with the spring portion  151 . 
   In  FIG. 25B , the lever main body  9  (elongated rod-like portion) is formed as an integrated component with the screw fixing portion  8  and the hook portion  7 . In a normal state, the tip of the latch portion  6  and a claw portion  161  are projected from an end portion of the lever main body  9 . A slip stopper and a predetermined shape are designed on the surface of the lever main body  9 . A contact portion  152  to the chassis is provided on the other end of the lever main body  9 . Next to the contact portion  152 , the screw fixing portion  8  is connected integrally, and further, the hook portion  7  is connected integrally. The screw fixing portion  8  is fixed to the module side with screw and functions as a fulcrum (rotary shaft). The hook portion  7  is located on an opposite side to the contact portion  152  with respect to the position of the screw fixing portion  8 . 
   In  FIG. 25C , the main body of the latch portion  6  is incorporated so as to be concealed behind the rear side of the front surface of the lever main body  9 . On the other side of the latch portion  6 , for example, its projecting portion is inserted partly into the spring portion  151 . The fastening portion  162  of the latch portion  6  is fastened by being hooked to the wall of the hole portion  153  in the lever main body  9 , and the position (initial position in normal state) of the latch portion  6  is thus determined. The spring portion  151  is flexed when the latch portion  6  is pressed in the internal direction of the lever main body  9 , and the latch portion  6  can be moved by a predetermined length. 
   In this configuration, in consideration of the operation by an end user, the lever main body  9  (screw fixing portion  8  and hook portion  7 ) is colored in a color different from that of the module main body, for example, black, and further, the latch portion  6  is colored in another different color, for example, blue. By this coloring, the components can be distinguished visibly in association with the contents of the operation (rotating action of the lever main body  9  and pressing action of the latch portion  6 ). The same coloring method is employed for all the operation levers  5  so that the portions which the user touches are colored in the same uniform colors. In this manner, visibility of the components is improved, thereby improving the operability. 
   As for the size of the operation lever  5 , the length (x 1 ) thereof in the direction of the lever main body  9  is 55.7 mm, the length (y 1 ) in the depth direction including the screw fixing portion  8  is 21.5 mm, and the width (z 1 ) is 11 mm. 
   Different from the conventional technology, the operation lever  5  does not employ any screw parts by providing the latch portion  6 . Accordingly, handling of the screw parts and any special tool relating to the operation of the module is eliminated to reduce labor and time. Further, confusion with screw parts used in the module itself is prevented, thereby improving the operability. 
   Also, the operation lever  5  has a structure which can be disassembled to respective components (lever main body  9 , latch portion  6 , spring portion  151  and the like) easily without using any special tool. When disassembling the operation lever  5 , the user presses the fastening portion  162  of the latch portion through the hole portion  153  in the front surface of the lever main body  9  of the operation lever  5 . By this means, the hook of the fastening portion  162  to the lever main body  9  is released and the latch portion  6  is detached, and also the spring portion  151  therein is taken out. 
   &lt;Attachment of Operation Lever and Operation State&gt; 
     FIG. 26  and  FIG. 27  show an attachment structure and operation state of the operation lever  5  to the chassis and the module. The description will be made using the CTL module  10  and the operation lever  104  as examples.  FIG. 26  shows a module fixing state (corresponding to  FIG. 28A ) and  FIG. 27  shows a module releasing state (corresponding to  FIG. 28D ). The module is moved by a predetermined stroke (ST) between the states shown in  FIG. 26  and  FIG. 27 . 
   In  FIG. 26 , the latch portion  6  is fixed to the receiving portion  156  which is a part of the module (front surface  106 ) by an action A of moving down the lever main body  9  of the operation lever  5  and an action a of pressing the latch portion  6 . By the above-described actions, the spring portion  151  is flexed and the latch portion  6  is moved by a predetermined length (p), and the claw portion  161  gets into the interior of the receiving portion  156 . Consequently, the claw portion  161  is hooked and fixed to the wall of the receiving portion  156  by an elastic force of the spring portion  151 . 
   The screw fixing portion  8  is attached to a part of the area of the module, that is, a notched (recessed portion) area  171  at the corner of the CTL module  10  (partial internal arrangement/mounting structure). The tip of the hook portion  7  gets into a part of the area on the chassis side, that is, the interior of the receiving portion  157  of the partition plate  95 , and is then hooked and fixed to the wall. 
   In  FIG. 27 , the latch portion  6  is released from the receiving portion  156  which is a part of the module (front surface  106 ) by an action b of pressing the latch portion  6  of the operation lever  5  and an action B of moving up the lever main body  9  (in other words, action of moving it toward an operator). By the above-described actions, the spring portion  151  is flexed and the latch portion  6  is moved by a predetermined length (p), and the claw portion  161  comes from inside of the receiving portion  156  to outside. Consequently, the latch portion  6  is returned to its initial position by an elastic force of the spring portion  151 . The tip of the hook portion  7  comes out of the receiving portion  157  of the partition plate  95  on the chassis side and the hooking thereof is released. Further, the contact portion  152  of the lever main body  9  gets contact with the front wall of the partition plate  95  on the chassis side. 
   Although the stroke (ST) for moving of the module is set to a predetermined length (14 mm) in this embodiment, any other lengths can be used. 
   &lt;Operation of Operation Lever&gt; 
   The operations for insertion/removal and fixation of the module (for example, CTL module  10 ) having the operation lever  5  to/from the area in the chassis by a user (maintenance person or end user) and corresponding mechanism will be described below with reference to  FIG. 28A  to  FIG. 28D . 
   (1) Insertion of module: The module (for example, CTL module  10 ) is inserted and fixed into the area in the chassis by a user in the following manner. A user inserts a module into the area in the chassis through an opening surface and moves down the lever main body  9  of the operation lever  5  (by this means, the module is connected to a connector on the backboard side). Then, along with this action (consecutively), the latch portion  6  at the tip of the lever main body  9  is pressed toward the deep side so that the latch portion  6  is fixed to the receiving portion  156 . At the same time, the hook portion  7  of the operation lever  5  is fixed to the receiving portion  157  on the chassis side. By this means, the module is fixed. In a series of actions described above, it is assumed that the latch portion  6  at the tip completes insertion and fixation of the module without any special operation. This will be described in detail below. 
   (1-1)  FIG. 28D  shows a state d, that is, the state of a stroke position when the module is inserted into the internal area of the chassis or the state of releasing the fixation of the module. A user holds the module and the operation lever and inserts the rear surface side of the module into the internal area of the chassis through an opening surface of the chassis, and then pushes it toward the deep side along the guide rail. The module is inserted up to a position at which the operation lever stands at right angle with respect to the module surface and the operation lever gets contact with the chassis (partition plate  95 ). The module is located at a position at which it projects by an amount equivalent to the stroke of the operation lever from a fixing position in the internal area of the chassis. 
   (1-2)  FIG. 28C  shows a state c, that is, a state at the middle of the operation of inserting the module (action A). More specifically, the module is moved by an amount equivalent to the stroke from the position of the state d to a fixing position by the action based on the principle of leverage using the operation lever, that is, by the action A of rotating the lever main body  9  to move down the same with respect to the module front surface ( 106 ). By this means, the module is completely inserted into the internal area of the chassis. At the same time, the connector ( 111 ) on the rear surface of the module is connected to the connector ( 201 ) on the backboard (the connectors are coupled with each other). 
   (1-3)  FIG. 28B  shows a state b, that is, a state when the latch portion  6  is fixed (action a). Along with the action A of moving down the lever main body  9  in the state c (consecutively), the action a of pressing the latch portion  6  at the tip of the lever main body  9  into the lever main body  9  smoothly is performed. In this manner, the spring portion  151  is flexed and the claw portion  161  of the latch portion  6  gets into the inside of the receiving portion  156  on the module side (or chassis side). 
   Although the description of the action a to the latch portion  6  is clearly separated from that of the action A for the easy understanding, the action a is automatically achieved by the motions of the claw portion  161  of the latch portion  6  and the spring portion  151  only by the action A which is unconscious of the action a. That is, as described above, insertion and fixation of the module are completed without any special operation. 
   (1-4)  FIG. 28A  shows a state a, in which the module is fixed. Subsequent to the action in the state b, the claw portion  161  of the latch portion  6  is hooked and fixed (latched or locked) to the inside of the receiving portion  156  (latch action). At the same time, the hook portion  7  is hooked and fixed to the inside of the receiving portion  157  on the chassis side. In this manner, the module is fixed completely. In this state a, the lever main body  9  keeps a parallel contact with the module surface, the latch portion  6  is completely fixed to the receiving portion  156 , and the hook portion  7  is completely fixed to the receiving portion  157 . In other words, the module is connected to the backboard through connectors. 
   (2) Removal of module: The operation by a user for removing the module (for example, CTL module  10 ) from the internal area of the chassis and releasing the fixation thereof is as follows. In the module fixation state, a user presses the latch portion  6  at the tip of the lever main body  9  and simultaneously (consecutively) moves up (pulls) the lever main body  9  to move the same toward the side of the user. Consequently, the fixing state of the latch portion  6  to the receiving portion  156  is released, and at the same time, the fixing state of the hook portion  7  to the receiving portion  157  on the chassis side is released. Also, the other tip of the lever main body  9  is brought into a contact with a part of the chassis by the principle of leverage, and the hook portion  7  comes out of the inside of the receiving portion  157  on the chassis side. In this manner, the connectors of the module are disconnected, and the module itself is released from the fixing state. Further, when the lever main body  9  is moved up (pulled) toward the user, the module is moved by an amount equivalent to a predetermined stroke (ST) toward the user from the internal area of the chassis or the fixing position, and after that, the module can be removed completely by detaching the same. The detail will be described below. 
   (2-1)  FIG. 28A  shows a state a, that is, a module fixing state. The lever main body  9  is located in parallel to the module surface, the latch portion  6  is completely fixed to the receiving portion  156 , and the hook portion  7  is fixed completely to the receiving portion  157 . In other words, the module is connected to the backboard through connectors. 
   (2-2)  FIG. 28B  shows a state b, that is, a state when the fixation of the latch portion is released (action b). A user grips the operation lever of the module and presses the latch portion  6  at the tip of the lever main body  9  toward the interior of the lever main body  9 . By this means, the fixing state of the claw portion  161  of the latch portion  6  to the inside of the receiving portion  156  on the module side (or chassis side) is released. 
   (2-3)  FIG. 28C  shows a state c, that is, a state at the middle of the operation of removing the module (action B). Subsequent to the state b, the module is moved so that it comes out by an amount equivalent to the predetermined stroke (ST) by the action based on the principle of leverage. That is, along with the action in the state b (consecutively), the lever main body  9  is rotated smoothly so as to move up the same (pull) toward the user with respect to the front surface of the module ( 106 ). By the action to move up (pull) the lever main body  9 , the other tip (contact portion  152  on an opposite side to the latch portion  6 ) of the lever main body  9  is pressed against a part of the chassis (front side of the receiving portion  157  of the partition plate  95 ), and the hook portion  7  comes out of the inside of the receiving portion  157  on the chassis side by the principle of leverage. In this manner, the fixing state of the latch portion  6  to the receiving portion  156  on the module side (or chassis side) is released, and simultaneously, the hooking of the hook portion  7  to the receiving portion  157  on the chassis side is also released. The consecutive actions of the pressing action of the latch portion  6  and the rotating (moving up) action of the lever main body  9  is achieved by only sliding the lever main body  9  slightly sideway while pressing the latch portion  6 . Accordingly, this is a smooth action with a small load. 
   (2-4)  FIG. 28D  shows a state d, that is, a state when the module is removed from the internal area of the chassis (at stroke (ST) position) or the state of releasing the fixation of the module. When the rotation of the lever main body  9  ends and the lever main body  9  stands at right angle with respect to the module surface, the module is moved by an amount equivalent to a predetermined stroke (ST) obtained by that action toward the user from the fixing position in the area of the chassis and it is projected outside. Thereafter, the module is detached by moving it toward the user along guide rails. In this manner, it is taken out of the internal area of the chassis. 
   &lt;Structure of Operation Lever (2)&gt; 
   Next, a different structure (example of the structure) of the operation lever  5  will be described as another embodiment. Each structure example exists as variations of the structure of the latch portion  6 , the hook portion  7 , the screw fixing portion (rotary shaft portion)  8 , and the lever main body  9 . 
   An operation lever  5 A as a second structure example will be described with reference to  FIG. 29  (sectional structure). In this operation lever  5 A, a latch portion  6 A (for example, blue) is attached to an integrated structure (for example, black) including a lever main body  9 A, a rotary shaft portion  8 A, and a hook portion  7 A. This structure does not need the spring portion  151 . Different from the first structure example, the latch portion  6 A is not disposed at the front tip side of the lever main body  9 A but on the other tip side (contact portion  152  side) near the screw fixing portion  8 A (fulcrum point). A part of the latch portion  6 A is projected from a hole portion  153 A on the fulcrum side of the lever main body  9 A. A claw portion  161 A of the latch portion  6 A is disposed between the hole portion  153 A and the screw fixing portion  8 A. When a user presses a part of the latch portion  6 A (shifts it in the right or left direction), the latch portion  6 A itself is deformed to displace the claw portion  161 A, and the claw portion  161 A is hooked and fixed to or released from the receiving portion  156 . The structures of the receiving portions ( 156 ,  157 ) on the chassis side and module side are the same as those of the first structure example. 
   &lt;Structure of Operation Lever (3)&gt; 
   An operation lever  5 B as a third structure example will be described with reference to  FIG. 30 . Similar to the second structure example ( 5 A), in the operation lever  5 B, a latch portion  6 B is not disposed on the front tip side of a lever main body  9 B but on the other tip side. Further, the latch portion  6 B has a rotary shaft portion, and a spring portion  151 B is attached to the rotary shaft portion. By the action of pressing a part of the latch portion  6 B projecting from a hole portion  153 B in the lever main body  9 B (by shifting it in the right or left direction), a force of the spring portion  151 B is applied, and the claw portion  161 B on the other tip is fixed to or released from the receiving portion  156 . 
   &lt;Structure of Operation Lever (4)&gt; 
   An operation lever  5 C as a fourth structure example will be described with reference to  FIG. 31 . In the operation lever  5 C, a lever main body  9 C and a latch portion  6 C (particularly a claw portion  161 C) are integrated. Also, a screw fixing portion  8 C, a hook portion  7 C, and a contact portion  152 C are integrally formed of plate metal. A spring portion  151 C is incorporated in the lever main body  9 C. When the fixation of the module is released, the latch portion  6 C is released to rotate the lever main body  9 C. 
   &lt;Structure of Operation Lever (5)&gt; 
   An operation lever  5 D as a fifth structure example will be described with reference to  FIG. 32 . Similar to the first structure example, in the operation lever  5 D, a latch portion  6 D (particularly a claw portion  161 D and a portion to be pressed by a user) is disposed on the front tip side of a lever main body  9 D. The lever main body  9 D, a screw fixing portion  8 D, and a hook portion  7 D are integrated, and a rod-like construction which is the latch portion  6 D is attached thereto. The latch portion  6  is disposed on the rear side of the front surface of the lever main body  9 D. Similar to the first structure example, on the other end side of the structure of the latch portion  6  near the other tip of the lever main body  9 D, an area  154  in which a spring portion (not shown) is incorporated is provided. When releasing the fixation of the module, the fixing state is released by pressing a part of the latch portion  6  on the front tip side of the lever main body  9 D. 
   The first and fifth structure examples have an advantage that the rotating action of the lever main body  9  and the latching action can be easily associated and the operation thereof is easy to execute because the latch portion  6  (portion to be pressed by a user) is disposed on the front tip side of the lever main body  9 . Further, the second to fourth structure examples have an advantage that processing of the receiving portion  156  (hole portion or the like) on the chassis side or module side with respect to the latch portion  6  is not necessary (shared by the receiving portion  157  with respect to the hook portion  7 ). 
   &lt;Power Source Module—Safety Mechanism&gt; 
   Further, a configuration example of a safety mechanism related to a power source system (including an operating structure) provided in a power source module ( 40  and  80 ) will be described with reference to  FIG. 33  to  FIG. 38 .  FIG. 33  shows the case where the mechanism is provided in the power source module  40  on the rear surface (B) of the basic chassis  100 , and  FIG. 34  to  FIG. 38  show the case where the mechanism is provided in the power source module  80  on the rear surface (D) of the expanded chassis  200 . Note that this safety mechanism is basically similar on the side of the power source module  40  and on the side of the power source module  80  (detailed shapes may be different depending on the module mounting states), and the description will be made based on the example on the side of the power source module  80 . 
   In this disk array system, with the adoption of the common operation lever  5  described above, a protection and prevention mechanism for erroneous operations (safety mechanism) including operating structures related to the operation of the power source cable and others (for example, lever lock members  454  and  854 ) and associated with the operation of the operation lever  5  ( 46  and  86 ) (that is, insertion and removal of modules) is provided in the power source module ( 40  and  80 ). Briefly, by this safety mechanism, the insertion and removal of the modules by the operation lever  5  ( 46  and  86 ) in a state where the power source cable ( 452  and  852 ) remains inserted in the power source module ( 40  and  80 ) become impossible. 
   Basically, in the power source module  40  in  FIG. 33  (only a part on the right side of the basic chassis  100  is shown), a power source cable connector  451  to which the power source cable  452  is connected (inserted) is provided at a position between the exhaust holes  48  in the module surface. Further, at the position of the connector  451 , a retainer  453  for the power source cable  452  is provided. Also, the lever lock member  454  for realizing the safety function is provided at a position between the connector  451  as well as the retainer  453  and the operation lever  46  of the power source module  40 . 
   Similarly, in the power source module  80  in  FIG. 34  (only a lower right part of the expanded chassis  200  is shown), a power source cable connector  851  to which the power source cable  852  is connected (inserted) is provided at a position adjacent to the exhaust hole of the fan ( 82 ) and at the middle of the right side of the module surface. Further, at the position of the connector  851 , a retainer  853  for the power source cable  852  is provided. Also, the lever lock member  854  for realizing the safety function is provided at a position between the connector  851  as well as the retainer  853  and the operation lever  86  of the power source module  80 . 
   Further, LEDs (light emitting diode)  470  and  870  showing a state of the power source (for example, ready (green) state and alarm (red) state) are provided in a part of the power source module ( 40  and  80 ). 
   In the configuration of the power source module ( 40  and  80 ), the power source switch (for switching ON and OFF the power source) is not provided on the module surface. Therefore, ON and OFF states of the power source are determined by the insertion and removal states of the power source cable ( 452  and  852 ) to and from the power source module ( 40  and  80 ) and the insertion state of the power source module. More specifically, in a state where the power source module ( 40  and  80 ) is inserted and the power source cable ( 452  and  852 ) is inserted, the power source is in an ON state. On the other hand, in a state where the power source module ( 40  and  80 ) is removed or the power source cable ( 452  and  852 ) is removed, the power source is in an OFF state. Note that ON and OFF of the disk array system can be controlled by a switch of the panel  60 . 
   Since the power source switch is not provided, a mechanism (formed from wires or the like) for preventing the accidental removal of the power source cable ( 452  and  852 ), that is, a retainer ( 453  and  853 ) is provided. By the retainer ( 453  and  853 ), the accidental removal of the power source cable ( 452  and  852 ) itself can be prevented. 
   The lever lock member ( 454  and  854 ) that is the characteristic of this embodiment is a component for preventing the removal of the power source module ( 40  and  80 ) in a state where the power source cable ( 452  and  852 ) remains inserted. By providing the lever lock member ( 454  and  854 ), in a state where the power source cable ( 452  and  852 ) remains inserted, the operation lever ( 46  and  86 ) is fixed, and thus the removal of the power source module ( 40  and  80 ) itself is impossible in principle. 
   Since this disk array system has the configuration formed in consideration of that an end user conducts the operations related to each of the modules including the power source module ( 40  and  80 ) (user maintenance support), the power source detachment mechanism is simplified. More specifically, the mechanism in which the power source module ( 40  and  80 ) is inserted and removed using the operation lever ( 46  and  86 ) by an end user is provided as described above. Therefore, in the case where only the conventional power source cable retaining mechanism (retainer ( 453  and  853 ) and the like) is provided (in the case where the lever lock member ( 454  and  854 ) is not provided), the operation of removing the power source module ( 40  and  80 ) by the operation of the operation lever ( 46  and  86 ) (latch release and the like) can be conducted in principle even in a state where the power source cable ( 452  and  852 ) remains inserted. Although such an operation is not desirable, there is the possibility that an uninitiated end user may conduct the operation by mistake. In such a case, the effect on the human body due to the secondary failure of the power source is of a concern. Further, even if one of the duplex (two) power source modules ( 40  and  80 ) is removed by the operation mentioned above, there is no problem on the performance of the power source system, but the state where both of the duplex modules are properly connected is of course more desirable. 
   Accordingly, in this embodiment, as the mechanism capable of automatically preventing such an erroneous operation described above (insertion and removal of power source module in a power source cable inserted state), the safety mechanism composed of the lever lock member ( 454  and  854 ) is provided in addition to the operation lever  5  and the retainer ( 453  and  853 ). With this mechanism, when the power source cable ( 452  and  852 ) is inserted into the connector ( 451  and  851 ), due to the positional change of the lever lock member ( 454  and  854 ) by the rotation thereof, the operation lever ( 46  and  86 ) of the power source module ( 40  and  80 ) is automatically put into an inoperable fixed state (state where the latch cannot be released). Therefore, the above-mentioned erroneous operation by the user can be prevented. Since the series of operations are simple and consecutive and do not require any particular intention for an end user, and the above-mentioned effect can be automatically achieved without adding troublesome procedures and difficult operations. More detailed description will be made below. 
   In the case of the power source module  80 , as an example of the detailed structure of the lever lock member  854 , a metal body in an approximate L-shape in accordance with the arrangement between the operation lever  86  and the connector  851  has a first end portion  861  (lever side fixing portion), a second end portion  862  (power source cable side fixing portion), a rotary shaft portion  863  and an exhaust hole portion  864 . The first end portion  861  is a portion for fixing the operation lever  86 , and it has a cover portion in the form of an L-shaped claw in accordance with the shape of the operation lever  86  as shown in  FIG. 38 . The second end portion  862  is a portion abutting to the connector  851  and the power source cable  852 , and it has a surface portion to which the power source cable  852  is pressed. The rotary shaft portion  863  is a portion fixed to the surface of the power source module  80  by screwing and others. The exhaust hole portion  864  is provided so as not to interfere with the exhaustion when the lever lock member  854  is placed over the exhaust hole of the fan ( 82 ). 
     FIG. 34  (and  FIG. 35 ) shows the state A, in which the power source cable  852  is not inserted into the connector  851  (retainer  853  is laid), the operation lever  86  is not fixed by the lever lock member  854 , and the power source module  80  can be inserted or removed.  FIG. 36  (and  FIGS. 37 and 38 ) shows the state B, in which the power source cable  852  is inserted into the connector  851  (fixed by the retainer  853 ), the operation lever  86  is fixed by the lever lock member  854 , and the power source module  80  cannot be inserted or removed. At first, this system is offered to an end user in the state A. Then, the end user conducts the operation of inserting the power source cable  852  to bring the power source into an ON state, thereby achieving the state B. On the other hand, when the power source is brought into an ON state by the end user and the power source module  80  is taken out, from the state B, the power source cable  852  is removed and then the power source module  80  is removed by the operation of the operation lever  86 . 
   In the state A, the terminal face of the connector  851  is opened and the lever lock member  854  is in an inclined state, and the power source cable  852  can be inserted by pushing away the second end portion  862  of the lever lock member  854 . When the second end portion  862  is pushed, the lever lock member  854  rotates around the rotary shaft portion  863 , and the first end portion  861  moves to the position where it covers a part of the operation lever  86 , for example, a part adjacent to an end portion thereof (including a front surface side) ( FIG. 38  and the like). This is the state where the power source cable  852  is inserted into the connector  851  and the operation lever  86  is fixed (locked) by the lever lock member  854 . In succession to the operation described above, the retainer  853  is moved up (state B). In this manner, a part of the retainer  853  (convex portion) is engaged with a part of the power source cable  852 . Consequently, even if the power source cable  852  is pulled in a removal direction due to the erroneous operation, the removal can be prevented by the engagement. Meanwhile, since the operation lever  86  is fixed (locked) by the first end portion  861 , it is possible to prevent the end user from removing the power source module by pushing the latch portion  6  on the front tip of the operation lever  86  to move up the operation lever  86 . 
   In the state B, the power source cable  852  is inserted into the connector  851  and fixed by the retainer  853 , and the operation lever  86  is fixed (locked) by the lever lock member  854 . When the power source module  80  is to be removed, from the state B, the retainer  853  is moved down and the power source cable  852  is removed from the connector  851  by an end user. Subsequently, the lever lock member  854  automatically rotates around the rotary shaft portion and is in an inclined state, and the cover by the first end portion  861  over the operation lever  86  is taken off (state A). As a result, the operation of pushing the latch portion  6  of the operation lever  86  to move up the operation lever  86  becomes possible, and the operation of the operation lever  86  is conducted by the end user and the power source module  80  is removed. 
   Additionally, the power source state of the basic chassis  100  will be described below. A user can control the ON and OFF operation of the switch provided on the surface of the panel  60 . When the switch is in an OFF state, the power source of the disk array system is in a Ready state. In the Ready state, power is supplied to a part of the CTL module  10  and the backboard  20 . When the switch is brought into an ON state by the operation of the user, power is supplied to the whole of the CTL module  10 , and the whole of the disk array system is started up. Further, the power source state of the expanded chassis  200  will be described below. The ON and OFF states of the expanded chassis  200  are switched by the insertion and removal of the power source cable ( 852 ). Even when the switch of the panel  60  of the basic chassis  100  is brought into an OFF state, the power supply is maintained unless the power source cable ( 852 ) of the expanded chassis  200  is removed. 
   The power source system in a state where the power source cable ( 452  and  852 ) is inserted in this disk array system will be described below. The power source module ( 40  and  80 ) is provided with a decision circuit, and no voltage is supplied to the output side (backboard  20 , CTL module  10  and others) unless the state where the power source module is normally inserted (connected) into the backboard  20  is achieved. However, from an aspect of the safety standard of a power source, the system in which voltage is supplied to the output side even with the single failure (failure in one of duplex (two) modules) is considered undesirable in general. In the design of the power source system including the power source module ( 40  and  80 ) in this disk array system, basically, the voltage is supplied to the output side even with the signal failure mentioned above. Therefore, in this disk array system, the safety mechanism described above is adopted so that the power source module ( 40  and  80 ) cannot be removed from the chassis in the state where the power source cable ( 452  and  852 ) remains inserted. 
   Since the safety mechanism of the power source system related to the common operation lever  5  is provided, the erroneous operation can be prevented and the operability for a user can be improved. 
   Effects of the Embodiments 
   As described above, although plural types of operating structures corresponding to plural types of modules coexist conventionally, according to the embodiments described above, those operating structures are standardized and the operability of the entire disk array system and all the modules is improved. Further, a necessity of using special knowledge about operation of the module or any special tool such as screw driver is eliminated and a mistake in operation of screws or the like of the module itself can be avoided. Therefore, it is possible to provide a disk array system suitable for the operation by an end user. 
   In the foregoing, the invention made by the inventors of the present invention has been concretely described based on the embodiments. However, it is needless to say that the present invention is not limited to the foregoing embodiments and various modifications and alterations can be made within the scope of the present invention. 
   The present invention can be applied to a disk array system which needs to be provided with a cooling structure for a heat generating portion such as HDD.