Patent Publication Number: US-7908513-B2

Title: Method for controlling failover processing for a first channel controller and a second channel controller

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation application of and claims priority to U.S. patent application Ser. No. 10/757,958, filed Jan. 13, 2004, now U.S. Pat. No. 7,305,670, issued Dec. 4, 2007, which claims priority upon Japanese Patent Application No. 2003-011595 filed on Jan. 20, 2003, all of which are herein incorporated by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of installing software on a storage device controlling apparatus, a method of controlling a storage device controlling apparatus, and a storage device controlling apparatus. 
     2. Description of the Related Art 
     In recent years, the amount of data handled by computer systems has been greatly increased. As storage systems for managing these data, large-scale storage systems called a mid-range class or enterprise class, managed according to a RAID (Redundant Arrays of Inexpensive Disks) method which provides an enormous storage source, are drawing attention these days. Moreover, to efficiently manage the enormous amount of data, a technology has been developed, in which an exclusive network (Storage Area Network; hereinafter referred to as SAN) connects information processing apparatuses and a storage system such as a disk array apparatus to implement high-speed and massive access to the storage system. 
     Meanwhile, a storage system called a NAS (Network Attached Storage) has been developed, in which a network using TCP/IP (Transmission Control Protocol/Internet Protocol) protocols, etc., connects a storage system and information processing apparatuses to implement access in file level from the information processing apparatuses (e.g., Japanese Patent Application Laid-Open Publication No. 2002-351703). 
     However, a conventional NAS has been achieved by connecting information processing apparatuses having TCP/IP communication and file system functions to a storage system without TCP/IP communication and file system functions. Therefore, installation spaces have been required for the abovementioned information processing apparatuses to be connected. Moreover, the information processing apparatuses and storage system are usually connected by a SAN in order to perform high-speed communication. Thus, the information processing apparatus has been required to be provided with a communication controlling apparatus or a communication controlling function. Furthermore, in order to make the storage system work as a NAS, it has been required to install a piece of software on each of the storage system without the TCP/IP communication and file system functions, and the information processing apparatuses having the TCP/IP communication and file system functions, and further to perform various settings to link those pieces of software. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the abovementioned problems, and the main object of the present invention is to provide a method of installing software on a storage device controlling apparatus, a method of controlling a storage device controlling apparatus, and a storage device controlling apparatus. 
     In order to solve the abovementioned problems, the method according to the present invention of installing software on a storage device controlling apparatus is a method of installing software on a storage device controlling apparatus which includes at least one channel controller having a circuit board on which are formed a file access processing section receiving requests to input and output data in files as units from an information processing apparatus via a first network and an I/O processor outputting I/O requests corresponding to the requests to input and output data to a storage device; at least one disk controller executing input and output of data into and from the storage device in response to the I/O requests sent from the I/O processor; and a second network connecting the channel controller and the disk controller so as to be able to communicate with each other, the method comprising the step of: writing software for making the file access processing section function, into the storage device by communicating with the channel controller via the second network. 
     Note that the information processing apparatus is, for example, a personal computer or a mainframe computer which accesses a storage system comprising the storage device controlling apparatus having the abovementioned structure via LAN or SAN. The function of the file access processing section is provided by an operating system executed on CPU and software such as NFS (Network File System) which runs on this operating system. The storage device is a disk drive such as a hard disk unit. The I/O processor comprises, for example, an IC (Integrated Circuit) separate from the CPU as a hardware element, which is the hardware element of the file access processing section, and controls the communication between the file access processing section and the disk controller. The disk controller writes and reads data into and from the storage device. 
     Further, by installing firmware or software to make the file access processing section work in the storage device, the storage system can provide the information processing apparatus with a function to work as a NAS. 
     Features and objects of the present invention other than the above will become clear by reading the description of the present specification with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a block diagram showing the entire construction of a storage system according to the present embodiment; 
         FIG. 2  is a block diagram showing the construction of a managing terminal according to the present embodiment; 
         FIG. 3  is a view showing a physical disk managing table according to the present embodiment; 
         FIG. 4  is a view showing an LU managing table according to the present embodiment; 
         FIG. 5  is a view showing the exterior structure of the storage system according to the present embodiment; 
         FIG. 6  is a view showing the exterior structure of a storage device controlling apparatus according to the present embodiment; 
         FIG. 7  is a view showing a CHN according to the present embodiment; 
         FIG. 8  is a view showing a CHF and CHA according to the present embodiment; 
         FIG. 9  is a view for explaining the contents of data stored in a memory according to the present embodiment; 
         FIG. 10  is a view showing a disk controller according to the present embodiment; 
         FIG. 11  is a view showing the structure of software according to the present embodiment; 
         FIG. 12  is a view showing the structure of a cluster in channel controllers according to the present embodiment; 
         FIG. 13  is a view showing metadata according to the present embodiment; 
         FIG. 14  is a view showing lock tables according to the present embodiment; 
         FIG. 15  is a block diagram for explaining the installing procedure according to the present embodiment; 
         FIG. 16  shows an example of the screen displayed on the output unit of the managing terminal to install the software according to the present embodiment; 
         FIG. 17  shows an example of the screen displayed in an information processing apparatus to set a cluster according to the present embodiment; 
         FIG. 18  is a flow chart showing the installing procedure according to the present embodiment; 
         FIG. 19  is a view showing ways clusters are so set that each cluster includes channel controllers connected to a plurality of systems of power supply; and 
         FIG. 20  is a view showing ways clusters are so set that each cluster includes channel controllers connected to a plurality of systems of power supply. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At least the following matters will be made clear by the explanation in the present specification and the description of the accompanying drawings. 
     An embodiment of the present invention will be described in detail below with reference to the drawings. 
       FIG. 1  is a block diagram showing the entire construction of a storage system  600  according to the present embodiment. 
     ===Example of the Entire Construction=== 
     The storage system  600  comprises a storage device controlling apparatus  100  and storage devices  300 . The storage device controlling apparatus  100  controls the storage devices  300  according to commands received from information processing apparatuses  200 . For example, when requests to input and output data are received from an information processing apparatus  200 , the storage device controlling apparatus  100  performs processing for the input and output of data stored in a storage device  300 . Data is stored in a memory area, a logical unit (hereinafter, referred to as LU) logically set in a physical memory area provided by the disk drive of the storage device  300 . The storage device controlling apparatus  100  also receives various commands from the information processing apparatuses  200  to manage the storage system  600 . 
     The information processing apparatus  200  is a computer having a CPU (Central Processing Unit) and a memory. Execution of various programs by the CPU provided in the information processing apparatus  200  implements various functions. The information processing apparatus  200  is, for example, a personal computer, a workstation or a mainframe computer. 
     In  FIG. 1 , the information processing apparatuses  1  to  3  ( 200 ) are connected to the storage device controlling apparatus  100  via a LAN (Local Area Network)  400 . The LAN  400  may be the Internet or an exclusive network. Communication between the information processing apparatuses  1  to  3  ( 200 ) and the storage device controlling apparatus  100  is performed via the LAN  400  according to, for example, TCP/IP protocols. The information processing apparatuses  1  to  3  ( 200 ) send the storage system  600  data access requests with specified file names (requests to input and output data in terms of files; hereinafter referred to as file access requests). 
     The LAN  400  is connected to a backup device  910 , which is specifically a disk-based device such as MO, CD-R or DVDRAM, or a tape-based device such as a DAT tape, cassette tape, open tape or cartridge tape. The backup device  910  communicates with the storage device controlling apparatus  100  via the LAN  400  to store backup data for data stored in the storage device  300 . Further, the backup device  910  can also be connected to the information processing apparatus  1  ( 200 ). In this case, backup data for data stored in the storage device  300  is acquired via the information processing apparatus  1  ( 200 ). 
     The storage device controlling apparatus  100  comprises channel controllers  1  to  4  ( 110 ). By the channel controllers  1  to  4  ( 110 ), the storage device controlling apparatus  100  communicates with the information processing apparatuses  1  to  3  ( 200 ) and the backup device  910  via the LAN  400 . The channel controllers  1  to  4  ( 110 ) individually accept file access requests from the information processing apparatuses  1  to  3  ( 200 ). That is, the channel controllers  1  to  4  ( 110 ) are assigned respective network addresses on the LAN  400  (e.g., IP addresses), and each behaves as a NAS so that each channel controller can provide service as NAS to the information processing apparatuses  1  to  3  ( 200 ) as if separate NASs were present. Hereinafter, the channel controllers  1  to  4  ( 110 ) are each referred to as CHN. Thus, one storage system  600  is constructed to have the channel controllers  1  to  4  ( 110 ), which individually provide service as the NAS, and thereby NAS servers, which are operated individually on separate computers in the conventional art, are integrated into one storage system  600 . Therefore, the entire storage system  600  can be managed so that various settings and controls, and maintenance such as fault management and version management are made more efficient. 
     Note that the channel controllers  1  to  4  ( 110 ) of the storage device controlling apparatus  100  according to the present embodiment are implemented by hardware formed on an integrally unitized circuit board and software such as an operating system (hereinafter, referred to as OS) executed by this hardware and application programs running on this OS, as described later. Thus, the functions of the storage system  600  according to the present embodiment, which are implemented as part of hardware in the conventional art, are implemented by software. Hence, the storage system  600  according to the present embodiment enables flexible system operation and can provide more finely tuned services to meet diverse and greatly varying user needs. 
     The information processing apparatuses  3 ,  4  ( 200 ) are connected to the storage device controlling apparatus  100  via a SAN (Storage Area Network)  500 . The SAN  500  is a network for the storage device controlling apparatus  100  to exchange data with the information processing apparatuses  3 ,  4  ( 200 ) in blocks, units for managing data in the memory area provided by the storage device  300 . The communication between the information processing apparatuses  3 ,  4  ( 200 ) and the storage device controlling apparatus  100  via the SAN  500  is performed usually according to a Fibre-Channel protocol. The information processing apparatuses  3 ,  4  ( 200 ) send requests to access data (hereinafter, referred to as block access requests) to the storage system  600  in blocks according to the Fibre-Channel protocol. 
     The SAN  500  is connected to a backup device  900  compatible with SAN, which communicates with the storage device controlling apparatus  100  via the SAN  500  to store backup data for data stored in the storage device  300 . 
     The storage device controlling apparatus  100  comprises channel controllers  5 ,  6  ( 110 ). By the channel controllers  5 ,  6  ( 110 ), the storage device controlling apparatus  100  communicates with the information processing apparatuses  3 ,  4  ( 200 ) and the backup device  900  compatible with SAN via the SAN  500 . Hereinafter, the channel controllers  5 ,  6  ( 110 ) are referred to as CHFs. 
     The information processing apparatus  5  ( 200 ) is connected to the storage device controlling apparatus  100  directly without a network such as the LAN  400  and the SAN  500 . The information processing apparatus  5  ( 200 ) may be, for example, a mainframe computer. The communication between the information processing apparatus  5  ( 200 ) and the storage device controlling apparatus  100  is performed according to a communication protocol such as FICON (Fibre Connection) (registered trademark), ESCON (Enterprise System Connection) (registered trademark), ACONARC (Advanced Connection Architecture) (registered trademark), or FIBARC (Fibre Connection Architecture) (registered trademark). The information processing apparatus  5  ( 200 ) sends the storage system  600  block access requests according to the communication protocol. 
     The storage device controlling apparatus  100  communicates with the information processing apparatus  5  ( 200 ) by the channel controllers  7 ,  8  ( 110 ). Hereinafter, the channel controllers  7 ,  8  ( 110 ) are referred to as CHAs. 
     The SAN  500  is connected to another storage system  610  installed at a place (secondary site) remote from the place (primary site) where the storage system  600  is installed. The storage system  610  is used as a unit into which data is duplicated by a function of replication or remote copy. It is noted that the storage system  610  may also be connected to the storage system  600  via a communication line such as ATM, instead of the SAN  500 . In this case, a channel controller  110  provided with an interface (channel extender) for using the abovementioned communication line is adopted. 
     According to the present embodiment, by installing CHNs  110 , CHFs  110 , and CHAs  110  together in the storage system  600 , a storage system connected to different types of networks can be implemented. Specifically, the storage system  600  is a SANNAS integrated storage system, which is connected to the LAN  400  via CHNs  110  and to the SAN  500  via CHFs  110 . 
     ===Storage Device=== 
     The storage device  300  comprises multiple disk drives (physical disks) and provides a memory area to the information processing apparatus  200 . Data is stored in an LU, a memory area logically set on a physical memory area provided by the disk drive. Various units such as a hard disk unit, a flexible disk unit and a semiconductor memory unit can be used as the disk drive. Note that the storage device  300  can be, for example, a disk array formed of a plurality of disk drives. In this case, the memory area may be provided to the information processing apparatus  200  by the plurality of disk drives managed by a RAID. 
     The storage device controlling apparatus  100  and the storage devices  300  may be connected directly as shown in  FIG. 1  or via a network. Alternatively, the storage devices  300  may be integrated with the storage device controlling apparatus  100 . 
     LUs set in the storage device  300  include user LUs accessible from the information processing apparatuses  200 , a system LU used for controlling a channel controller  110 , and the like. Stored in the system LU is an operating system executed in a CHN  110 . Each LU is made correspond to a channel controller  110 , and thereby each channel controller  110  is assigned accessible LUs. In the correspondence, a plurality of channel controllers  110  can share one LU. Hereinafter, the user LU and the system LU are also referred to as a user disk and a system disk, respectively. An LU shared by a plurality of channel controllers  110  is referred to as a shared LU or a shared disk. One example of the shared LU is a fault management LU that is defined in order to share the fault information between a plurality of channel controllers  110 . Another example of the shared LU is a cluster LU that is defined in order to share cluster management information between a plurality of channel controllers when they make up a cluster to be managed as a set and provide redundancy. Since the purpose of defining shared LUs and system LUs is to manage the system itself by the channel controllers, the shared LUs or system LUs need not be accessed by information processing apparatuses  200 , while user LUs can be accessed by information processing apparatuses  200 . 
     ===Storage Device Controlling Apparatus=== 
     The storage device controlling apparatus  100  comprises the channel controllers  110 , a shared memory  120 , a cache memory  130 , disk controllers  140 , a managing terminal  160 , and a connecting section  150 . 
     The channel controller  110  comprises a communication interface to communicate with the information processing apparatuses  200  and a function to receive data input and output commands, etc., from the information processing apparatuses  200 . For example, the CHNs  110  accept file access requests from the information processing apparatuses  1  to  3  ( 200 ) and obtain the memory addresses and data lengths of the files to output I/O requests corresponding to the file access requests so as to access storage devices  300 . Accordingly, the storage system  600  can provide service as a NAS to the information processing apparatuses  1  to  3  ( 200 ). Note that the I/O request includes the top address, data length, and type of access such as read or write, of data. When data is to be written, the I/O request may include data to be written. I/O requests are outputted by an I/O processor  119  described later. The CHFs  110  accept block access requests from the information processing apparatuses  3 ,  4  ( 200 ) according to the Fibre-Channel protocol. Thus, the storage system  600  can provide high-speed accessible data storage service to the information processing apparatuses  3 ,  4  ( 200 ). The CHAs  110  accept block access requests from the information processing apparatus  5  ( 200 ) according to a protocol such as FICON, ESCON, ACONARC, or FIBARC. Accordingly, the storage system  600  can provide data storage service to the information processing apparatus  5 , a mainframe computer. 
     The channel controllers  110  and the managing terminal  160  are connected by an internal LAN  151 . Accordingly, micro programs, etc., executed by the channel controllers  110  can be sent from the managing terminal  160  and installed therein. The construction of the channel controllers  110  is described later. 
     The connecting section  150  connects the channel controllers  110 , the shared memory  120 , the cache memory  130 , and the disk controllers  140 . Data and commands are sent and received to and from the channel controllers  110 , the shared memory  120 , the cache memory  130 , and the disk controllers  140  via the connecting section  150 . The connecting section  150  is constituted by, for example, a high-speed bus such as a superfast cross bus switch which transmits data by high-speed switching. Since the channel controllers  110  are connected each other by the high-speed bus, the communication performance between the channel controllers  110  is greatly improved over the conventional construction where the NAS servers operating on individual computers are connected via a LAN. This enables a high-speed file sharing function, high-speed fail-over, and the like. 
     The shared memory  120  and the cache memory  130  are memories shared by the channel controllers  110  and the disk controllers  140 . The shared memory  120  is mainly used to store control information, commands, etc., while the cache memory  130  is mainly used to store data. 
     For example, when a data input and output command received by a channel controller  110  from an information processing apparatus  200  is a write command, the channel controller  110  writes the write command into the shared memory  120  and data received from the information processing apparatus  200  into the cache memory  130 . Meanwhile, the disk controllers  140  are monitoring the shared memory  120 . When the disk controllers  140  detect that the write command has been written into the shared memory  120 , one of the disk controllers  140  reads the data from the cache memory  130  and writes the data into a relevant storage device  300  according to the command. 
     When a data input and output command received by a channel controller  110  from an information processing apparatus  200  is a read command, the channel controller  110  writes the read command into the shared memory  120  and checks whether to-be-read data is present in the cache memory  130 . If the data is present in the cache memory  130 , the channel controller  110  sends the data to the information processing apparatus  200 . On the other hand, if the to-be-read data is not present in the cache memory  130 , a disk controller  140  monitoring the shared memory  120  detects that the read command has been written into the shared memory  120  and reads the to-be-read data from a relevant storage device  300  to write the data into the cache memory  130  and a notice thereof in the shared memory  120 . Thereafter, when the channel controller  110  detects that the to-be-read data has been written into the cache memory  130  by monitoring the shared memory  120 , the channel controller  110  sends the data to the information processing apparatus  200 . 
     Note that other than the construction where instructions to write and read data are indirectly sent from the channel controller  110  to the disk controller  140  via the shared memory  120 , for example, the storage device controlling apparatus  100  may have construction where instructions to write and read data are sent directly from a channel controller  110  to a disk controller  140  without the shared memory  120 . 
     A disk controller  140  controls a storage device  300 . For example, as described above, according to a data write command received from an information processing apparatus  200 , a channel controller  110  writes the data into the storage device  300 . Further, a request sent from the channel controller  110  to access data in an LU designated by a logical address is converted into a request to access data in a physical disk designated by a physical address. If the physical disks in the storage device  300  are managed by RAID, data is accessed according to the structure of the RAID. Moreover, the disk controller  140  controls management of the duplication and backup of data stored in the storage device  300 . Furthermore, the disk controller  140  controls to store duplication of data in the storage system  600  at the primary site into another storage system  610  installed in the secondary site (a replication or remote copy function) for the purpose of preventing data loss in the occurrence of disaster (disaster recovery). 
     The disk controllers  140  and the managing terminal  160  are connected each other via the internal LAN  151  and can communicate with each other. This enables micro-programs, etc., executed by the disk controllers  140  to be sent from the managing terminal  160  and installed therein. The construction of the disk controllers  140  is described later. 
     In the present embodiment, the shared memory  120  and the cache memory  130  are provided separately from the channel controllers  110  and the disk controllers  140 . The present embodiment is not limited to this case. It is also preferable that the shared memory  120  or the cache memory  130  be dispersed to be provided in each of the channel controllers  110  and the disk controllers  140 . In this case, the connecting section  150  connects the channel controllers  110  and the disk controllers  140 , which have dispersed shared memories or cache memories. 
     ===Managing Terminal=== 
     The managing terminal  160  is a computer for maintaining and managing the storage system  600 . By operating the managing terminal  160 , it is possible to set the structure of the physical disks and LUs in the storage device  300  and install micro-programs executed by the channel controllers  110 . Herein, in the setting of the structure of the physical disks in the storage device  300 , for example, physical disks can be added or removed, and the RAID structure can be changed (e.g., a change from RAID1 to RAID5). Further, via the managing terminal  160 , it is possible to perform various operations, including: confirming the operation state of the storage system  600 ; identifying a fault section; and installing operating systems executed by the channel controllers  110 . Yet further, the managing terminal  160  is connected to an external maintenance center via a LAN, a telephone line, etc., so that it is possible to monitor faults in the storage system  600  and quickly deals with faults when occurred by use of the managing terminal  160 . The occurrence of faults is notified by, for example, OSs, application programs, driver software, etc. The faults are notified through a HTTP protocol, a SNMP (Simple Network Management Protocol), e-mails and the like. These are set and controlled by an operator and the like via a Web page serving as a user interface provided by a Web server operating on the managing terminal  160 . The operator and the like can also designate objects subjected to fault monitoring and set its contents and targets to be notified of faults. 
     The managing terminal  160  can be incorporated into the storage device controlling apparatus  100  or attached thereto externally. Further, the managing terminal  160  may be a computer which exclusively maintains and manages the storage device controlling apparatus  100  and the storage devices  300  or a general-purpose computer having a maintenance and management function. 
       FIG. 2  is a block diagram showing the construction of the managing terminal  160 . 
     The managing terminal  160  comprises a CPU  161 , a memory  162 , a port  163 , a storage medium reader  164 , an input unit  165 , an output unit  166 , and a storage unit  168 . 
     The CPU  161  controls the whole managing terminal  160  and implements functions and the like as the abovementioned Web server, etc., by executing a program  162   c  stored in the memory  162 . The memory  162  stores a physical disk managing table  162   a , an LU managing table  162   b , and the program  162   c.    
     The physical disk managing table  162   a  is a table for managing the physical disks (disk drives) provided in a storage device/storage devices  300 , and is shown in  FIG. 3 . In FIG.  3 , of the multiple physical disks provided in the storage device/storage devices  300 , disk numbers # 001  to # 006  are shown. The capacity, RAID structure, and usage state of each physical disk are shown. 
     The LU managing table  162   b  is a table for managing the LUs set logically on the abovementioned physical disks, and is shown in  FIG. 4 . In  FIG. 4 , of the multiple LUs set in the storage device  300 , LU numbers # 1  to # 3  are shown. The physical disk number, capacity, and RAID structure of each LU are shown. 
     The storage medium reader  164  is a unit for reading programs and data stored in a storage medium  167 . Read programs and data are stored in the memory  162  or the storage unit  168 . Accordingly, for example, the program  162   c  recorded in the storage medium  167  can be read by use of the storage medium reader  164  and stored in the memory  162  or the storage unit  168 . A flexible disk, a CD-ROM, a semiconductor memory, etc., can be used as the storage medium  167 . The storage medium reader  164  can be incorporated into the managing terminal  160  or attached thereto externally. The storage unit  168  is, for example, a hard disk unit, flexible disk unit, and a semiconductor memory unit. The input unit  165  is used by an operator, etc., to enter data, etc., into the managing terminal  160 . Used as the input unit  165  is, for example, a keyboard, or a mouse. The output unit  166  is a unit for outputting information to the outside. Used as the output unit  166  is, for example, a display, or a printer. The port  163  is connected to the internal LAN  151 , and thereby the managing terminal  160  can communicate with the channel controllers  110 , the disk controllers  140  and the like. Further, the port  163  can be connected to the LAN  400  or a telephone line. 
     ===Exterior Figure=== 
     Next,  FIG. 5  shows the exterior structure of the storage system  600  according to the present embodiment, and  FIG. 6  shows the exterior structure of the storage device controlling apparatus  100 . 
     As shown in  FIG. 5 , the storage system  600  according to the present embodiment has the storage device controlling apparatus  100  and the storage devices  300  contained in respective chassis. The chassis for the storage devices  300  are placed on both sides of the chassis for the storage device controlling apparatus  100 . 
     The storage device controlling apparatus  100  comprises the managing terminal  160  provided at the center front. The managing terminal  160  is covered by a cover, and the managing terminal  160  can be used by opening the cover as shown in  FIG. 6 . Note that while the managing terminal  160  shown in  FIG. 6  is a so-called notebook personal computer, it may take any form. 
     Provided under the managing terminal  160  are slots to which the channel controllers  110  are to be attached. The board of a channel controller  110  is attached to each slot. The storage system  600  according to the present embodiment has eight slots.  FIGS. 5 and 6  show a state where the eight slots have the channel controllers  110  attached thereto. Each slot is provided with guide rails to attach a channel controller  110 . By inserting the channel controller  110  into the slot along the guide rails, the channel controller  110  is attached to the storage device controlling apparatus  100 . By pulling the channel controller  110  toward the front along the guide rails, the channel controller  110  can be removed. Further, provided on the surface facing forwards in the back of each slot is a connector for connecting a channel controller  110  to the storage device controlling apparatus  100  electrically. The channel controllers  110  are CHNs, CHFs, and CHAs. Since each channel controller  110  is compatible with the others in size and in the position and pin arrangement of its connector and the like, the eight slots can have any channel controller  110  attached thereto. Therefore, for example, all the eight slots can have the CHNs  110  attached thereto. Alternatively, as shown in  FIG. 1 , the eight slots can have four CHNs  110 , two CHFs  110 , and two CHAs  110  attached thereto, or some of the slots may have no channel controller  110 . 
     Of the channel controllers  110  attached to the slots, plural channel controllers  110  of the same type constitute a cluster. For example, two CHNs  110  as a pair may constitute a cluster. By constituting a cluster, even when a fault has occurred in a channel controller  110  of the cluster, another channel controller  110  in the cluster may be arranged to take over processing that the channel controller  110 , where the fault has occurred, was performing until then (fail-over control).  FIG. 12  shows two CHNs  110  constituting a cluster, which is described in detail later. 
     Note that the storage device controlling apparatus  100  has two systems of power supply to improve reliability, and the abovementioned eight slots, to which channel controllers  110  are attached, are divided into two groups of four for the respective power supply systems. Hence, when forming a cluster, the cluster is arranged to include channel controllers  110  respectively connected to both power supply systems. Thus, even if a failure occurs in one of the power supply systems to stop supplying electric power, electric power continues to be supplied to another channel controller  110  connected to the other power supply system forming part of the same cluster. Therefore, another channel controller  110  can take over the processing from the relevant channel controller  110  (fail-over). 
     Note that, as described above, while each channel controller  110  is provided as a board that can be attached to any of the slots, that is, as a unit formed on the same board, the unit may include a plurality of boards. In other words, even if a unit is formed of a plurality of boards, the concept of the same circuit board includes a group of boards that are connected each other and integrated as a unit and can be integrally attached to a slot of the storage device controlling apparatus  100 . 
     Other units forming part of the storage device controlling apparatus  100 , such as the disk controllers  140  and the shared memory  120 , are not shown in  FIGS. 5 and 6 , but attached to the back, etc., of the storage device controlling apparatus  100 . 
     The storage device controlling apparatus  100  is provided with fans  170  for releasing heat generated in the channel controllers  110 , etc. The fans  170  are provided on the tops of the slots for the channel controllers  110  as well as on the top of the storage device controlling apparatus  100 . 
     For example, units having conventional structures that are manufactured complying with a SAN can be used as the storage device controlling apparatus  100  and the storage devices  300  contained in respective chassis. In particular, by making the connector&#39;s shape of the CHN take such a shape that it can be directly attached to a slot provided in a conventionally structured chassis as described above, the units having conventional structures can be used more easily. The storage system  600  according to the present embodiment can be easily constructed by using the existing products. 
     ===Channel Controller=== 
     As described above, the storage system  600  according to the present embodiment accepts file access requests from the information processing apparatuses  1  to  3  ( 200 ) by CHNs  110 , and provides service as a NAS to the information processing apparatuses  1  to  3  ( 200 ). 
     The hardware structure of a CHN  110  is shown in  FIG. 7 . As shown in  FIG. 7 , the CHN  110 &#39;s hardware is constituted as a unit. Hereinafter, this unit is referred to as a NAS board. The NAS board includes one or more circuit boards. More specifically, the NAS board comprises a network interface section  111 , a CPU  112 , a memory  113 , an input-output controller  114 , an I/O (Input/Output) processor  119 , an NVRAM (Non Volatile RAM)  115 , a board connecting connector  116 , and a communication connector  117 , which are formed as one unit. 
     The network interface section  111  comprises a communication interface for communicating with the information processing apparatuses  200 . In the case of a CHN  110 , the communication interface receives file access requests sent from the information processing apparatuses  200  according to, for example, TCP/IP protocols. The communication connector  117  is a connector for communicating with the information processing apparatuses  200 . In the case of a CHN  110 , the communication connector is a connector that can be connected to the LAN  400  and complies with, for example, Ethernet (registered trademark). 
     The CPU  112  controls the CHN  110  to function as a NAS board. 
     The memory  113  stores various programs and data. For example, metadata  730  and a lock table  720  shown in  FIG. 9  and various programs such as a NAS manager  706  shown in  FIG. 11  are stored. The metadata  730  is information created for files managed by a file system. The metadata  730  includes information for identifying the storage location of each file such as the address on an LU where the file data is stored and the data size. The metadata  730  may also include the capacity, owner, update time, etc., of each file. Further, the metadata  730  may be created not only for files but also for directories. An example of the metadata  730  is shown in  FIG. 13 . The metadata  730  is also stored in each LU in the storage device  300 . 
     The lock table  720  is a table for performing exclusive control on file accesses from the information processing apparatuses  1  to  3  ( 200 ). With exclusive access control, the information processing apparatuses  1  to  3  ( 200 ) can share files. The lock table  720  is shown in  FIG. 14 . As shown in  FIG. 14 , the lock table  720  includes a file lock table  721  and an LU lock table  722 . The file lock table  721  is a table for indicating whether it is locked for each file. When an information processing apparatus  200  has opened a file, the file is locked, to which access from other information processing apparatuses  200  is prohibited. The LU lock table  722  is a table for indicating whether it is locked for each LU. When an information processing apparatus  200  is accessing an LU, the LU is locked, to which access from other information processing apparatuses  200  is prohibited. 
     The input-output controller  114  sends and receives data and commands to and from the disk controllers  140 , the cache memory  130 , the shared memory  120 , and the managing terminal  160 . The input-output controller  114  comprises the I/O processor  119  and the NVRAM  115 . The I/O processor  119  is constituted by, for example, a one-chip micro-computer. The I/O processor  119  controls the sending and receiving of data and commands and relays communication between the CPU  112  and the disk controllers  140 . The NVRAM  115  is a nonvolatile memory storing a program to control the I/O processor  119 . The contents of a program stored in the NVRAM  115  can be written or rewritten according to instructions from the managing terminal  160  or the NAS manager  706  described later. 
     Next, the structures of the CHF  110  and the CHA  110  are shown in  FIG. 8 . The CHF  110  and the CHA  110  are also formed as units in the same way as the CHN  110 . Similar to the CHN  110 , this unit may be constructed from a plurality of circuit boards. Further, the CHF  110  and the CHA  110  are compatible with the CHN  110  in terms of size and the position and pin arrangement of the board connecting connector  116  and the like. 
     The CHF  110  and the CHA  110  comprise a network interface section  111 , a memory  113 , an input-output controller  114 , an I/O processor  119 , an NVRAM (Non Volatile RAM)  115 , a board connecting connector  116 , and a communication connector  117 . 
     The network interface section  111  comprises a communication interface for communicating with the information processing apparatuses  200 . In the case of a CHF  110 , the communication interface receives block access requests sent from the information processing apparatuses  200  according to, for example, the Fibre Channel protocol. In the case of a CHA  110 , the communication interface receives block access requests sent from the information processing apparatuses  200  according to, for example, FICON (registered trademark), ESCON (registered trademark), ACONARC (registered trademark), or FIBARC (registered trademark) protocol. The communication connector  117  is a connector for communicating with the information processing apparatuses  200 . In the case of a CHF  110 , the communication connector  117  is a connector that can be connected to the SAN  500  and complies with, for example, the Fibre Channel. In the case of a CHA  110 , the communication connector  117  is a connector that can be connected to the information processing apparatus  5  and complies with, for example, FICON (registered trademark), ESCON (registered trademark), ACONARC (registered trademark), or FIBARC (registered trademark). 
     The input-output controllers  114  control the whole respective CHFs  110  and CHAs  110  and send and receive data and commands to and from the disk controllers  140 , the cache memory  130 , the shared memory  120 , and the managing terminal  160 . By executing various programs stored in the memory  113 , the functions of the CHFs  110  and CHAs  110  according to the present embodiment are implemented. The input-output controller  114  comprises the I/O processor  119  and the NVRAM  115 . The I/O processor  119  controls the sending and receiving of data and commands. The NVRAM  115  is a nonvolatile memory storing a program to control the I/O processor  119 . The contents of a program stored in the NVRAM  115  can be written or rewritten according to instructions from the managing terminal  160  or the NAS manager  706  described later. 
     Next, the structure of the disk controllers  140  is shown in  FIG. 10 . 
     The disk controller  140  comprises an interface section  141 , a memory  143 , a CPU  142 , an NVRAM  144 , and a board connecting connector  145 , which are formed integrally as a unit. 
     The interface section  141  comprises a communication interface for communicating with the channel controllers  110 , etc., via the connecting section  150 , and a communication interface for communicating with the storage device  300 . 
     The CPU  142  controls the entire disk controller  140  and communicates with the channel controllers  110 , the storage device  300 , and the managing terminal  160 . By executing various programs stored in the memory  143  and the NVRAM  144 , the functions of the disk controller  140  according to the present embodiment are implemented. The functions implemented by the disk controller  140  are the control of the storage device  300 , RAID control, and duplication management, backup control, remote copy control, and the like of data stored in the storage device  300 . 
     The NVRAM  144  is a nonvolatile memory storing a program to control the CPU  142 . The contents of a program stored in the NVRAM  144  can be written or rewritten according to instructions from the managing terminal  160  or the NAS manager  706  described later. 
     The disk controller  140  comprises the board connecting connector  145 . By engaging the board connecting connector  145  with the connector on the storage device controlling apparatus  100 , the disk controller  140  is connected electrically with the storage device controlling apparatus  100 . 
     Next, the structure of software in the storage system  600  according to present embodiment is shown in  FIG. 11 . 
     Running on an operating system  701  is software including a RAID manager  708 , a volume manager  707 , a SVP manager  709 , a file system program  703 , a network controller  702 , a backup management program  710 , a fault management program  705 , and an NAS manager  706 . 
     The RAID manager  708  running on the operating system  701  provides functions to set parameters for RAID controllers  740  and to control the RAID controllers  740 . The RAID manager  708  accepts parameters and control instructions information from the operating system  701 , and other applications and the SVP running on the operating system  701 , sets the accepted parameters into a RAID controller  740 , and sends the RAID controller  740  control commands corresponding to the control instruction information. 
     Herein, the set parameters include, for example, parameters for defining storage devices (physical disks) forming a RAID group (specifying RAID group&#39;s structure information, stripe size, etc.), a parameter for setting a RAID level (e.g., 0, 1, or 5), and the like. Examples of the control commands which the RAID manager  708  sends to a RAID controller  740  are commands instructing to configure and delete a RAID and to change the capacity thereof, and a command requesting structure information of each RAID group. 
     The volume manager  707  provides virtualized logical volumes, into which LUs provided by the RAID controller  740  are further virtualized, to the file system program  703 . A virtualized logical volume is composed of more than one logical volume. 
     The main function of the file system program  703  is to manage the correspondence between file names designated in file access requests received by the network controller  702  and addresses on virtualized logical volumes in which the files are stored. For example, the file system program  703  identifies the address on a virtualized logical volume corresponding to a file name designated by a file access request. 
     The network controller  702  comprises two file system protocols, a NFS (Network File System)  711  and a Samba  712 . The NFS  711  accepts a file access request from a UNIX (registered trademark)-based information processing apparatus  200  on which the NFS  711  runs. On the other hand, the Samba  712  accepts a file access request from a Windows (registered trademark)-based information processing apparatus  200  on which a CIFS (Common Interface File System)  713  runs. 
     The NAS manager  706  is a program for confirming, setting, and controlling the operation state of the storage system  600 . The NAS manager  706  has a function as a Web server and provides a setting Web page for the information processing apparatuses  200  to set and control the storage system  600 . In response to HTTP (HyperText Transport Protocol) requests from the information processing apparatuses  1  to  3  ( 200 ), the NAS manager  706  sends data of the setting Web page to the information processing apparatuses  1  to  3  ( 200 ). By use of the setting Web page displayed in the information processing apparatuses  1  to  3  ( 200 ), a system administrator, etc., instructs to set and control the storage system  600 . Things that can be done by use of the setting Web page are, for example, LU management and setting (capacity management, capacity expansion and reduction, user assignment, etc.); the setting and control (setting of the addresses of the to-be-copied and the to-be-copied-into) concerning functions such as duplication management and remote copy (replication); the setting and control of the backup management program  710  described later; the management of redundantly structured clusters of CHNs, CHFs and CHAs (setting of the correspondence between the channel controllers, whereby, when one fails, another fails over; a fail-over method; etc.); version management of the OS and application programs running on the OS; and the management and setting of the operation state of a security management program  716  and update management (version management) of the security management program  716  providing functions concerning security of data, such as a virus detection program and virus extermination. The NAS manager  706  receives data concerning settings and controls sent from an information processing apparatus  200  due to the operation of the setting Web page and performs the settings and controls corresponding to the data. Thus, various settings and controls of the storage system  600  can be performed from the information processing apparatuses  1  to  3  ( 200 ). 
     The backup management program  710  is a program for backing up data stored in the storage devices  300  via LAN or SAN. The backup management program  710  provides a function of an NDMP (Network Data Management) protocol and communicates, according to the NDMP, with backup software complying with the NDMP operating on an information processing apparatus  200  via the LAN  400 . When a backup device  910  is connected to the information processing apparatus  200  via a SCSI, etc., data to be backed up is once read by the information processing apparatus  200  and sent to the backup device  910 . When the backup device  910  is connected to the LAN  400 , data to be backed up may be transferred to the backup device  910  from the storage system  600  directly without an information processing apparatus  200 . 
     The fault management program  705  is a program for controlling fail-over between the channel controllers  110  which form a cluster. 
     The SVP manager  709  provides the managing terminal  160  with various services according to requests from the managing terminal  160 . For example, the SVP manager  709  provides the managing terminal  160  with the contents of various settings concerning the storage system  600  such as the settings of LUs or RAIDs and makes reflected therein the various settings concerning the storage system  600  entered from the managing terminal  160 . 
     The security management program  716  implements functions of detecting computer viruses, monitoring invasion, update management of a computer virus detection program, extermination of viruses infected a computer, firewall, and the like. 
     Next,  FIG. 12  shows a cluster  180  constituted of two CHNs  110 .  FIG. 12  shows a case where the cluster  180  is composed of a CHN  1  (channel controller  1 )  110  and a CHN  2  (channel controller  2 )  110 . 
     As previously mentioned, the fail-over processing is performed between the channel controllers  110  constituting the cluster  180 . That is, if any fault occurs in CHN  1  ( 110 ) and it becomes impossible to continue a processing, the CHN  2  ( 110 ) takes over the processing that has been performed by the CHN  1  ( 110 ). The fault management program  705  executed by the CHN  1  ( 110 ), and the CHN  2  ( 110 ) implements the fail-over processing. 
     Both CHN  1  ( 110 ) and CHN  2  ( 110 ) execute the fault management program  705 , write in the shared memory  120  to indicate that the processing thereof is normally performed, and confirm each other whether the other has written. When one cannot detect the writing by the other, the one determines that a fault has occurred in the other and performs fail-over processing. In the fail-over processing, the processing that has been performed by the other is taken over via a shared LU  310 . 
     Further, the file access processing section of each of CHNs  110  forming the cluster  180  can manage the accessible information processing apparatus  1  to  3  ( 200 ). Accordingly, it can be achieved that only when a file access request is sent from the accessible information processing apparatus  1  to  3  ( 200 ), the CHN accepts the file access request. The accessible information processing apparatus  1  to  3  ( 200 ) is managed by recording the domain name of the IP address of the information processing apparatus  1  to  3  ( 200 ), which is allowed to access, in each CHN  110 &#39;s memory  113  beforehand. 
     Thus, even when the information processing apparatuses  1  to  3  ( 200 ) are connected to the storage system  600  via common LAN  400 , LUs can be assigned exclusively to the information processing apparatuses  1  to  3  ( 200 ), respectively. For example, when the information processing apparatuses  1  to  3  ( 200 ) are computers of respective different enterprises, storage service in which data confidentiality is maintained from the others can be provided to each of the information processing apparatuses  1  to  3  ( 200 ). 
     The abovementioned settings of each CHN  110  can be performed from the managing terminal  160  and the information processing apparatuses  1  to  3  ( 200 ). When the information processing apparatuses  1  to  3  ( 200 ) perform the settings, the information processing apparatuses  1  to  3  ( 200 ) use the setting Web page displayed in the information processing apparatuses  1  to  3  ( 200 ) by the NAS manager  706  running on the CHN  110  to do so. 
     ===Installing Processing=== 
     Next, a description is given of installing software necessary to make the storage system  600  according to the present embodiment function as a NAS. 
     In order to make the storage system  600  function as a NAS, an OS  701  executed by CHNs  110  needs to be installed. Micro-programs (firmware) executed by the CHNs  110  and the disk controllers  140  need to be also installed. Application programs such as the volume manager  707 , the file system program  703 , and the NAS manager  706  are also installed in the CHNs  110  as necessary. A remote copy control program  750 , a duplication management program  760 , etc., are installed in the disk controllers  140  as necessary. 
     The OS  701  and the application programs are stored in system LUs set in a storage device/storage devices  300 . An OS installed area, a memory area for detecting faults, a memory area for cluster information, etc., may be assigned to the system LUs. Stored in the memory area for detecting faults is information about fault management such as dump lists outputted by the OS  701  and the application programs (core dump, memory dump, and disk dump outputted due to abnormal terminations of OS  701 &#39;s kernel and daemon, and abnormality where a processing loops between a plurality of processes). Stored in the memory area for cluster information is information needed to set clusters of CHNs  110 . Thus, by setting memory areas for storing the OS  701  and the application programs in a storage device/storage devices  300 , CHNs  110  does not need to have such memory areas provided therein. 
     Further, the memory area for detecting faults and the memory area for cluster information can be provided in a fault management LU and a cluster LU separately from the system LUs. Note that, when the storage devices  300  are operated according to a method of RAID 5, the system LUs, the fault management LU, the cluster LU and the like are preferably dispersed among a plurality of parity groups, instead of being concentrated in only one parity group. This is because important data is stored in these LUs to operate the storage device controlling apparatus  100 . 
     Next, the procedure is described below of installing the OS  701  and the micro-programs necessary to make the storage system  600  function as a NAS. These programs are installed from the managing terminal (computer)  160 . 
       FIG. 15  is a block diagram for explaining the procedure of the installation.  FIG. 16  shows an example of the screen for the installation displayed on the output unit  166  of the managing terminal  160 . 
     In the block diagram of  FIG. 15 , the storage device controlling apparatus  100  is connected to information processing apparatuses  200  via a LAN (first network)  400  and accepts file access requests from the information processing apparatuses  200 . The storage device controlling apparatus  100  comprises the managing terminal  160 . The managing terminal  160  is connected to CHNs  110  and the disk controllers  140  via the internal LAN (second network)  151 . Micro-programs  770 , a loader  771 , an installer  772 , and an OS  773  are stored in the managing terminal  160 . These programs are stored in the memory  162  and storage unit  168  of the managing terminal  160 . One of the micro-programs  770  is written into NVRAMs  115  of CHNs  110 , and the other is written into NVRAMs  144  of the disk controllers  140 . The former is a program for controlling I/O processors  119  of CHNs  110 . The latter is a program for controlling CPUs  142  of the disk controllers  140 . The loader  771  and the installer  772  are programs used for CHNs  110  to read in the OS  773  stored in the managing terminal  160 . The OS  773  is installed in a system LU provided in the storage device  300  for each CHN  110 . These programs can be read in from the storage medium  167  such as CD-ROM by use of the storage medium reader  164  provided to the managing terminal  160 , or downloaded via the port  163  from, for example, the Internet. 
     Further, an example of the screen displayed on the output unit  166  of the managing terminal  160  shown in  FIG. 16  is an example where CHNs  110  newly attached to slots No.  1  to  4  are set. Note that while the contents of settings for slots No.  5  to  8  are displayed in  FIG. 16 , those for slots already set may be for example non-displayed so that an operator cannot enter the settings thereof. 
     The install setup screen shown in  FIG. 16  includes a slot number column, a channel adaptor selection column, a system LU number designation column, and a boot designation column. Among them, an operator can enter the channel adaptor selection column, the system LU number designation column, and the boot designation column. 
     The types of channel controllers  110  to be attached to the slots of the storage device controlling apparatus  100  are entered into the channel adaptor selection column. The types of channel controllers  110  are CHA, CHF, and CHN. These items can be selected by clicking on portions indicated by downward triangle marks in  FIG. 16 . 
     System LU numbers are entered into the system LU number designation column. As a system LU, any LU can be selected from LUs set in the storage device  300 . A system LU is designated for each CHN  110 . Note that when the storage capacity of the LU designated as a system LU is less than a given capacity, the OS  773  and the like cannot be installed in that LU. Therefore, the managing terminal  160  comprises a function of checking the capacity of LUs entered in the system LU number designation column. Note that a system LU may also be shared by a plurality of CHNs  110 . 
     Methods of booting the channel controllers  110  are entered in the boot designation column. In the case of a via-network boot, a channel controller  110  is booted from the managing terminal  160  connected via the internal LAN  151 . In the case of a disk boot, a channel controller  110  is booted from a system LU on the storage device  300 . These designations can be selected by clicking with a mouse on portions indicated by downward triangle marks in  FIG. 16 . 
     After entering for slots No.  1  to  4  as shown in  FIG. 16 , an operator clicks on the OK button. Accordingly, the managing terminal  160  starts sequentially installing the programs in the CHNs  110  attached to slots No.  1  to  4 . 
     The flow chart of  FIG. 18  shows the installing procedure. According to instructions from an operator operating the managing terminal  160 , a micro-program rewriting program executed in the managing terminal  160  stores the MAC (Media Access Control) addresses of the CHNs  110  and disk controllers  140  into which the micro-programs  770  are written in, for example, the memory  162  of the managing terminal  160 , the addresses being pieces of information for identifying the CHNs  110  and disk controllers  140 . The micro-programs  770  (S 1000 ) are written into the NVRAMs  115  and  144  of CHNs  110  and disk controllers  140  identified by MAC addresses stored in the managing terminal  160 , respectively. The writing is performed through the internal LAN from the managing terminal  160 . Ones into which the micro-programs  770  are written can be determined based on input information from the abovementioned install setup screen. The MAC addresses of ones into which the micro-programs  770  are written are acquired by sending a MAC address inquiry command to CHNs  110  or disk controllers  140  connected to the internal LAN  151 . Note that information for identifying the CHNs  110  or disk controllers  140  stored in the managing terminal  160  is not limited to the MAC addresses but may be IP addresses or production numbers of the CHNs  110  and disk controllers  140 . The micro-programs  770  may be provided by the storage medium  167  such as CD-ROM or downloaded via the Internet. 
     As described above, by arranging the micro-programs  770  to be written into CHNs  110  and disk controllers  140  whose MAC addresses are stored in the managing terminal  160 , the micro-programs  770  can be written into only the specific CHNs  110  and disk controllers  140 . In this way, the micro-programs  770  can be written into only CHNs  110  and disk controllers  140  whose the micro-program/micro-programs  770  need be rewritten. Furthermore, the micro-program  770  for the CHNs  110  can be prevented from being mistakenly loaded into CHAs  110  or CHFs  110 . 
     Subsequently, the specific CHNs  110  and disk controllers  140  are reset, thereby making the micro-programs  770  installed start running. Herein, the reset is performed by, for example, the managing terminal  160 . After the reset, the managing terminal  160  comes to be able to recognize the LUs of the storage device/storage devices  300  when the disk controllers  140  have started operating. 
     Next, the managing terminal  160  sends instructions to read in the loader  771  to the CHNs  110  whose MAC addresses are stored in the managing terminal  160 . The loader  771  is a program executed by the CHNs  110  to read in the installer  772  from the managing terminal  160 . The instructions from the managing terminal  160  to read in the loader  771  are accepted and executed by BIOS (Basic Input/Output System) in CPUs  112  of the CHNs  110 , and thereby the CHNs  110  reads in the loader  771  from the managing terminal  160  (S 1001 ). 
     Subsequently, the loader  771  reads in the installer  772  from the managing terminal  160  (S 1002 ). The installer  772  provides functions to format LUs on a file system base and to write a file into an LU as well as functions concerning communications over the internal LAN  151 . 
     Next, the installer  772  sets partitions for the system LU in order to secure an installing area for the OS  773 , and formats the system LU as a file system (S 1003 ). The installer  772  reads in the OS  773  from the managing terminal  160  and writes in files into the formatted installing area (S 1004 ). Furthermore, the installer  772  makes the setup file for the written OS  773  reflect the network settings of the internal LAN  151 . 
     Yet further, the installer  772  writes a starting code for a MBR (Master Boot Record) into the system LU where the OS  773  has been written, and validates MBR (S 1005 ). Thus, the OS  773  is arranged to automatically start upon the reset of the CHN. 
     After the completion of the above processing, the I/O processors  119  of the CHNs  110  notify the managing terminal  160  of the completion of the installation via the internal LAN  151  (S 1006 ). 
     The managing terminal  160  repeats the installing processing successively for the respective CHNs  110  of slots No.  1  to  4  (S 1007 ). The completion of the above processing for all the CHNs  110  of slots No.  1  to  4  ends the installing processing. 
     By this installing method, firmware and the OS  773  can be installed smoothly in the procedure, the series of steps. 
     Subsequently, the CHNs are set as NASs. The settings of a CHN as a NAS include the granting of an IP address, user area settings, OS settings, and cluster settings. These settings are performed by a NAS manager  110 . An IP address is granted to each of the two communication ports of each CHN  110 . The user area settings are to create a file system for the user LU. The OS settings are to set a mount point on the file system created for the user LU and to perform user definitions, group definitions, etc. 
     ===Cluster Settings=== 
     The cluster settings are to divide the plurality of channel controllers  110  attached to the storage device controlling apparatus  100  into groups in terms of the types of channel controllers  110 . Accordingly, even when a fault occurs in a channel controller  110  in a cluster (group), another channel controller  110  in the cluster can be arranged to take over the processing that the channel controller  110 , where the fault has occurred, was performing until then. 
     The storage system  600  according to the present embodiment comprises two systems of power supply to improve reliability. Each slot of the storage device controlling apparatus  100  is connected to one of the two systems of power supply. In setting a cluster, the cluster is arranged to include both channel controllers  110  connected respectively to the two systems of power supply. That is, the cluster is so arranged that all channel controllers  110  therein are not connected to only one of the two systems of power supply. 
     In this way, if a power supply system stops supplying power due to a fault therein, the other power supply system continues to supply power to another channel controller  110  in the same cluster connected thereto. Therefore, the processing is failed over to another channel controller  110 . 
     An example of the screen for setting a cluster displayed in an information processing apparatus  200  is shown in  FIG. 17 .  FIGS. 19 and 20  show how to set a cluster so as to include both channel controllers  110  connected respectively to the two systems of power supply. 
     The screen for setting a cluster has a power supply system column, a slot number column, a board ID column, a board type column, a column  1  for setting the to-fail-over, a column  2  for setting the to-fail-over, and a shared LU setting column. 
     The power supply system column shows a power supply system of each slot. As in the example of the screen of  FIG. 17 , odd-numbered slots are connected to a power supply system A, and even-numbered slots are connected to a power supply system B. 
     The board ID column shows the board ID of the channel controller  110  attached to each slot, the board ID is, for example, a production number or IP address. 
     The board type column shows the type of the channel controller  110  attached to each slot, the type being of CHN, CHA, or CHF. 
     The column  1  for setting the to-fail-over is an input column for designating another board to fail over the processing when a fault has occurred in the board. These designations can be selected by clicking with a mouse on portions indicated by downward triangle marks in  FIG. 17 . 
     The column  2  for setting the to-fail-over is an input column for designating a second board to fail over the processing when the board designated in the column  1  for setting the to-fail-over cannot take over the processing. These designations can also be selected by clicking with a mouse on portions indicated by downward triangle marks in  FIG. 17 . 
     The shared LU setting column is an input column for designating an LU accessible from and shared among the channel controllers  110  forming the cluster. The shared LU stores take-over information, etc., needed in fail-over processing. 
     After entering theses inputs, an operator clicks on a set button. Accordingly, this setting information is sent to the storage device controlling apparatus  100 . It is checked whether the channel controllers  110  forming the cluster are connected solely to one power supply system, A or B. 
     If connected solely to one power supply system A or B, a warning is outputted to the user interface provided by the information processing apparatus  200 . When the information processing apparatus  200  is provided with a buzzer, the buzzer is set off. Alternatively, the display unit provided in the information processing apparatus  200  displays an error message. When the channel controllers  110  forming the cluster are connected to both power systems A and B, this setting information is stored in the memory  113  of each channel controller  110  and the shared LU, and this completes the cluster setup. Note that this setting information can be arranged to be stored in the storage area for cluster information of the system LU and the cluster LU as well. In addition, these cluster setups can be arranged to be performed from the managing terminal  160 . 
     Next,  FIGS. 19 and 20  show ways clusters are so set that each cluster includes channel controllers  110  connected to the two systems of power supply, respectively. 
     As previously mentioned, the storage device controlling apparatus  100  comprises the eight slots, and there is no restriction on a combination of a slot and a channel controller  110 . It is also possible to attach CHFs  110 , CHAs  110 , and CHNs  110  together thereto.  FIGS. 19 and 20  show an example of the cluster setup where only CHNs  110  are attached. 
       FIG. 20  shows examples where two CHNs  110  are attached, where four CHNs  110  are attached, and where six CHNs  110  are attached. As shown in  FIG. 20 , because the CHNs  110  forming the cluster have the same power source, the combinations (b), (e), (f), and (h) cause an error. 
       FIG. 19  shows examples where eight CHNs  110  are attached. Because the CHNs  110  forming the cluster have the same power source, the combination (I) causes an error. 
     As described above, in the storage system  600  according to the present embodiment, the cluster setup is performed such that the channel controllers  110  are not connected solely to one power supply system. Accordingly, even if a power supply system stops supplying power due to a fault therein, the processing can be failed over to another channel controller  110  in the same cluster connected to the other power supply system. Therefore, the highly applicably storage system  600  can be provided. 
     Although the preferred embodiment of the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.