Abstract:
The invention relates to an enclosure structure of electronic equipment such as a rack-mount disk array apparatus, and its object is to increase the number of apparatus units to be mounted and facilitate replacement thereof. The enclosure structure of electronic equipment of the invention having an enclosure mounted in a rack in a withdrawable manner, is arranged such that it comprises a plurality of wiring panel portions that partition the inner space of the enclosure in the fore-and-aft direction, the plurality of wiring panel portion being disposed spanning over the inner surface portions of the enclosure; and a movable frame portion that rotationally moves apparatus units connected to the wiring panel portions together with the wiring panel portions, the movable frame portion providing a support to the apparatus units in such a manner as to be attachable to and detachable from the wiring panel portions.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an enclosure structure of electronic equipment such as a rack-mount disk array apparatus.  
         [0003]     2. Description of the Related Art  
         [0004]     Reference is made to  FIG. 1  to describe a conventional rack-mount disk array apparatus. In a disk array apparatus  2 , there is provided a back panel  6  at the middle portion of an enclosure  4  mounted to the rack, with a plurality of hard disk units  8  provided on the front surface portion of the back panel  6  and a plurality of interface (I/F) units  10  and power supply units  12  provided on the rear surface portion of the back panel  6 . The hard disk units  8  are mounted from the front surface side of the enclosure  4  for replacement thereof.  
         [0005]     Japanese Patent Application Laid-Open Publication Nos. 2003-36669, 2002-343075, 08-137631 and 06-215553 are available as patent documents related to such an enclosure structure of electronic equipment such as such disk array apparatus.  
         [0006]     In Japanese Patent Application Laid-Open Publication No. 2003-36669, there are disclosed electronic equipment and a rack housing the electronic equipment in which, for easy replacement of hard disk devices in a rack-housed server unit, the server unit is configured with outer and inner cases, with a movable portion capable of moving downward attached to the inner case and hard disk devices housed in two rows, and in which, in the case of replacement of hard disk devices located toward the back, the inner case is drawn out, and further the movable portion is lowered so as to expose the end surfaces of the hard disk devices located toward the back. In such a configuration, all hard disk devices can be replaced from the front surface side, with no need to detach the server unit from the rack at the time of replacement.  
         [0007]     In Japanese Patent Application Laid-Open Publication No. 2002-343075, there is disclosed a disk array that allows easy performance of tasks such as replacement and addition of hard disk units and prevents occurrence of shorting failure as a result of contact between signal cable and slim enclosure. In this disk array, a plurality of slim enclosures, each equipped with a hard disk unit, are housed in a rack so as to be slidable, with the slim enclosures provided with a tray having a front opening for allowing entry of the hard disk unit so as to be freely attachable/detachable and a connector for connecting the hard disk unit that has entered from the front opening. The tray is supported so as to be movable to the disk attachment/detachment position that brings the front opening away from the bottom plate of the slim enclosure and to the use position that brings the front opening close to the bottom plate.  
         [0008]     In Japanese Patent Application Laid-Open Publication No. 08-137631, there is disclosed a disk array apparatus in which 2.5-inch or smaller hard disks can be installed using the form factor of 5.25-inch or 3.5-inch hard disk of a conventional disk array apparatus. As its configuration, four 2.5-inch hard disks are arranged three-dimensionally in a slot corresponding with the form factor of 5.25-inch hard disk of disk array apparatus. In the event of a failure of a hard disk, one pulls out the slot by grabbing the handle at the front of the slot, pulls out the faulty hard disk by grabbing the handle located toward the front, replaces the faulty hard disk with a new one, inserts the new hard disk into the slot by reversing the procedure for withdrawal and puts the slot back into the disk array apparatus to complete hot-swap.  
         [0009]     In Japanese Patent Application Laid-Open Publication No. 06-215553, there is disclosed an easy-to-install-and-detach disk drive carrier assembly that is equipped with a 3.5-inch disk head assembly (HDA) and an electronic card pack in a detachable manner.  
         [0010]     Incidentally, description will be given of hard disk units mounted in such a disk array apparatus with reference to  FIGS. 2A and 2B .  FIG. 2A  shows a case in which 3.5-inch hard disk (HDD) units are mounted in a rack, whereas  FIG. 2B  shows a case in which 2.5-inch hard disk-units are mounted in the same rack. In these disk array apparatuses  2 , size reduction of hard disk units  8 , mounted in the enclosure  4 , for example, from 3.5-inch type to 2.5-inch type, will result in a reduced storage capacity per unit height of the rack if the same unit arrangement is used as in the conventional apparatus.  
         [0011]     In a disk array apparatus  2 A shown in  FIG. 2A , the size of the 3.5-inch hard disk units  8  mounted in a rack  14  is 3U, thus making the height 36U due to a 12-stage configuration. Here, 1U=44.45 mm (1.75 inches) based on EIA standard. Letting the number of the hard disk units  8  installed in the direction of width of the rack  14  be 15, the storage capacity of each of the hard disk units  8  be, for example, 300 GB, and the storage capacity per the rack  14  in this case be M 1 , then the storage capacity M 1  is: 
 
 M   1 =12×15×300 [GB]=54,000 [GB]
 
         [0012]     In this case, the storage capacity per 1U or M 1 /36U is: 
 
 M   1 /36 U= 54,000 [GB]/36 U= 1,500 [GB]
 
         [0013]     In contrast, in a disk array apparatus  2 B shown in  FIG. 2B , the size of 2.5-inch hard disk units  18  mounted in a rack  16  is 2U, thus making the height 36U similarly due to an 18-stage configuration. Letting the number of the hard disk units  18  installed in the direction of width of the rack  16  be 24, the storage capacity of each of the hard disk units  18  be, for example, 73 GB, and the storage capacity per the rack  16  in this case be M 2 , then the storage capacity M 2  is: 
 
 M   2 =18×24×73 [GB]=31,536 [GB]
 
 In this case, the storage capacity per 1U or M 2 /36U is: 
 
 M   2 /36 U= 31,536 [GB]/36 U= 876 [GB]
 
         [0014]     Thus, if the 3.5-inch hard disk units  8  are changed to the 2.5-inch hard disk units  18 , the storage capacity per the rack  16  is low, despite increased number of the hard disk units  18 , because the storage capacity of each of the hard disk units  18  is low, thus resulting in 50 percent reduction in storage capacity per 1U. In addition, unless the storage capacity of the 2.5-inch hard disk units  18  increases, it is impossible to complement the decrease in storage capacity by increased number of units alone when the 3.5-inch hard disk units  8  are changed to the 2.5-inch hard disk units  18 . It is therefore necessary for the disk array apparatus  2 B to implement a structure that allows mounting of additional hard disk units in the apparatus and replacement thereof.  
         [0015]     With regard to such a problem, there is no disclosure in Japanese Patent Application Laid-Open Publication Nos. 2003-36669, 2002-343075, 08-137631 and 06-215553, nor is there any description of means for solving the problem.  
       SUMMARY OF THE INVENTION  
       [0016]     The present invention relates to an enclosure structure of electronic equipment such as a rack-mount disk array apparatus, and it is an object of the present invention to increase the number of apparatus units to be mounted and facilitate replacement thereof.  
         [0017]     It is another object of the present invention to provide a disk array apparatus that allows increased number of hard disk units to be mounted and that facilitates replacement thereof.  
         [0018]     In order to achieve the above objects, according to a first aspect of the present invention there is provided an enclosure structure of electronic equipment having an enclosure mounted in a rack in a withdrawable manner, the enclosure structure comprising a plurality of wiring panel portions that partition the inner space of the enclosure in the fore-and-aft direction, the plurality of wiring panel portion being disposed spanning over the inner surface portions of the enclosure; and a movable frame portion that rotationally moves apparatus units connected to the wiring panel portions together with the wiring panel portions, the movable frame portion providing a support to the apparatus units in such a manner as to be attachable to and detachable from the wiring panel portions.  
         [0019]     This enclosure structure of electronic equipment is applied to various types of electronic equipment such as a disk array apparatus, having an enclosure mounted in a rack in a withdrawable manner. Apparatus units to be mounted in the enclosure are connected to wiring panel portions. The wiring panel portions are provided in the fore-and-aft direction, spanning over inner surface portions of the enclosure, with the enclosure partitioned in the fore-and-aft direction by the plurality of wiring panel portions. Apparatus units are mounted in a partitioned space portion. In the enclosure provided with the plurality of wiring panel portions, apparatus units are mounted in each wiring panel portion, with the apparatus units in the fore-and-aft direction installed spanning over the wiring panel portions. There is provided, for this reason, a movable frame portion for facilitating attachment/detachment of the apparatus units on the back side when there are provided the apparatus units on the front side. The movable frame portion moves the apparatus units connected to the wiring panel portions rotationally together with their wiring panel portions, thus allowing for attachment/detachment of the apparatus units to/from the wiring panel portions and easy replacement of the apparatus units through the attachment/detachment. And, by applying such an enclosure structure to, for example, the disk array apparatus, it is possible to enhance the mounting density of hard disk units serving as the apparatus units, thus boosting the storage capacity and facilitating replacement thereof.  
         [0020]     In the enclosure structure of electronic equipment, a rotational motion mechanism may further be provided that supports the movable frame portion on the enclosure in such a manner as to be rotationally movable, the rotational motion mechanism rotationally moving the movable frame portion by a given angle. By virtue of such a configuration, it is possible to attach/detach the apparatus units with the movable frame portion moved rotationally.  
         [0021]     In the enclosure structure of electronic equipment, the rotational motion mechanism may include a supporting shaft supporting the movable frame portion on the enclosure in such a manner as to be rotationally movable; a gear mechanism intervening between the supporting shaft and the enclosure; and a spring intervening between the enclosure and the movable frame portion, the spring imparting a force of rotational motion derived from a restoration force to between the movable frame portion and the enclosure.  
         [0022]     In such a configuration, the movable frame portion, supported on the enclosure by a supporting shaft, is rotationally movable via a gear mechanism provided between the movable frame portion and the enclosure. Additionally, the restoration force of the spring acts in the spreading direction. For this reason, the movable frame portion rotates by receiving the restoration force of the spring via the gear mechanism, thus making it possible to extract the apparatus units from the enclosure. In this case, the gear mechanism eases, through gear ratio, the rotational force resulting from the restoration force of the spring, thus cushioning the impact of rotation of the movable frame portion on the apparatus units.  
         [0023]     In the enclosure structure of electronic equipment, a fixing mechanism may further be provided that fixes the movable frame portion to the enclosure against the restoration force of the spring. By virtue of such a configuration, rotation of the movable frame portion is blocked by the fixing mechanism, thus allowing the movable frame portion to be stably held within the enclosure.  
         [0024]     In the enclosure structure of electronic equipment, the fixing mechanism may include a locking portion disposed in the movable frame portion, the locking portion blocking rotational motion by becoming caught on a member of the enclosure; and an expansion/contraction portion permitting rotational motion of the movable frame portion by unlocking the locking portion.  
         [0025]     In order to achieve the above objects, according to a second aspect of the present invention there is provided a disk array apparatus comprising an enclosure mounted in a rack in such a manner as to be withdrawable; a plurality of wiring panel portions disposed within the enclosure; and hard disk units connected to the wiring panel portions, the hard disk units being disposed in a plurality of stages in the direction of height of the enclosure, in a plurality of rows in the direction of width of the enclosure, and in a plurality of columns in the fore-and-aft direction of the enclosure.  
         [0026]     In such a configuration, the plurality of wiring panel portions are provided in the enclosure mounted in a rack in a withdrawable manner, with the space in the enclosure being partitioned. In the partitioned space, there are provided a plurality of hard disk units, a plurality of stages in the direction of height of the enclosure, a plurality of rows in the direction of width of the enclosure and a plurality of columns in the fore-and-aft direction of the enclosure. This therefore boosts the number of hard disk units mounted within the rack, thus complementing decrease in storage capacity by increased number of hard disk units mounted even if hard disk units with low storage capacity are installed and thereby achieving the desired storage capacity.  
         [0027]     In order to achieve the above objects, according to a third aspect of the present invention there is provided a disk array apparatus mounted with hard disk units in an enclosure disposed in a rack in such a manner as to be withdrawable, the disk array apparatus comprising a plurality of wiring panel portions that partition the inner space of the enclosure in the fore-and-aft direction, the plurality of wiring panel portions being disposed spanning over the inner surface portions of the enclosure; and a movable frame portion that rotationally moves hard disk units connected to the wiring panel portions together with the wiring panel portions, the movable frame portion providing a support to the hard disk units in such a manner as to be attachable to and detachable from the wiring panel portions.  
         [0028]     In this disk array apparatus, similar to the above enclosure structure, a rotational motion mechanism may further be provided that supports the movable frame portion on the enclosure in such a manner as to be rotationally movable, the rotational motion mechanism rotationally moving the movable frame portion by a given angle. A sliding mechanism may further be provided that enables the enclosure to be withdrawn from the rack. The rotational motion mechanism may include a supporting shaft supporting the movable frame portion on the enclosure in such a manner as to be rotationally movable; a gear mechanism intervening between the supporting shaft and the enclosure; and a spring intervening between the enclosure and the movable frame portion, the spring imparting a force of rotational motion derived from a restoration force to between the movable frame portion and the enclosure.  
         [0029]     In the disk array apparatus, a fixing mechanism may further be provided that fixes the movable frame portion to the enclosure against the restoration force of the spring. The fixing mechanism may include a locking portion disposed in the movable frame portion, the locking portion blocking rotational motion by becoming caught on a member of the enclosure; and an expansion/contraction portion permitting rotational motion of the movable frame portion by unlocking the locking portion.  
         [0030]     As described above, the present invention relating to an enclosure structure of electronic equipment such as disk array apparatus is advantageous in that it boosts the number of apparatus units mounted and facilitates attachment/detachment and replacement thereof and that it is applicable to a variety of equipment using enclosures and racks.  
         [0031]     According to the enclosure structure of electronic equipment of the present invention, therefore, it is possible to boost the number of apparatus units mounted and facilitate replacement thereof.  
         [0032]     According to the disk array apparatus of the present invention, on the other hand, it is possible to not only enhance the storage capacity by boosting the number of hard disk units mounted but also facilitate replacement thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     Other objects, features and advantages of the present invention will become more apparent from the following description of embodiments when taken in conjunction with the accompanying drawings, in which:  
         [0034]      FIG. 1  is a perspective view showing an enclosure mounted in a conventional disk array apparatus;  
         [0035]      FIGS. 2A and 2B  show disk array apparatuses for comparison of storage capacity of hard disk units mounted in conventional racks, with  FIG. 2A  being a view showing a disk array apparatus equipped with 3.5-inch hard disk units, and  FIG. 2B  being a view showing a disk array apparatus equipped with 2.5-inch hard disk units;  
         [0036]      FIG. 3  is a perspective view showing the enclosure mounted in a disk array apparatus according to an embodiment of the present invention;  
         [0037]      FIG. 4  is a block diagram showing a configuration of the disk array apparatus in which the enclosure serves as a unit;  
         [0038]      FIG. 5  is a perspective view showing the disk array apparatus mounting the enclosure of 1U;  
         [0039]      FIG. 6  is a perspective view showing extraction of the hard disk unit from the enclosure mounted in the rack;  
         [0040]      FIG. 7  is a perspective view showing extraction of the enclosure from the rack;  
         [0041]      FIG. 8  is a perspective view showing the outline of a fixing mechanism of a movable frame portion;  
         [0042]      FIG. 9  is a partial sectional view showing part of the enclosure shown with the movable frame portion closed;  
         [0043]      FIG. 10  is a partial sectional view showing part of the enclosure shown with the movable frame portion open;  
         [0044]      FIG. 11  is an exploded perspective view showing an open/close mechanism;  
         [0045]      FIG. 12  is an exploded perspective view showing the fixing mechanism that is partially cut out;  
         [0046]      FIG. 13  is a perspective view showing extraction of the hard disk unit on the side of the movable frame portion; and  
         [0047]      FIG. 14  is a sectional view showing an example of a sliding mechanism. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0048]     An embodiment of the present invention will now be described. The present embodiment discloses, as an embodiment of an enclosure structure of electronic equipment, a disk array apparatus. Description will be given of the disk array apparatus with reference to  FIG. 3 .  FIG. 3  is a perspective view showing a configuration within the enclosure of the disk array apparatus.  
         [0049]     In a disk array apparatus  20 , an enclosure  22  is a flat container in the form of a rectangular parallelepiped made of a rigid material such as metal or synthetic resin, with the height h being set to, for example, 1U (44.5 [mm]) in EIA standard. On the front surface portion of the enclosure  22 , there is provided an opening portion  24 , with U-shaped handles  28  attached to flange portions  26  provided on the left and right of the opening portion  24 . On the side surface portions of the enclosure  22 , there is attached a slide rail  32  for a sliding mechanism  30 .  
         [0050]     Inside the enclosure  22 , there are provided a plurality of back panels  34 ,  36  and  38  as wiring panel portions spanning between the side surface portions, with the inner space of the enclosure  22  partitioned by the three back panels  34 ,  36  and  38 . On the front side of the back panels  34  and  36 , there are provided unit installation portions  40  and  42  for the hard disk units, whereas on the back side of the back panel  38 , there is provided a unit installation portion  44  for other equipment. In the present embodiment, the back panels  34  and  36  on the front side are, for example, provided with a spacing corresponding with the 2.5-inch hard disk unit. In the unit installation portion  40 , there are provided 10 hard disk units  46 F, two vertically and five horizontally. Similarly in the unit installation portion  42 , there are provided 10 hard disk units  46 B, two vertically and five horizontally. In this case, the number of the hard disk units  46 F and  46 B provided in the single enclosure  22  is  20  units. In the unit installation portion  44 , on the other hand, there are provided interface (I/F) units  48  and  49  vertically at the center portion, with power supply units  50  and  52  provided to sandwich the I/F units  48  and  49 .  
         [0051]     Description will be given next of a configuration of the disk array apparatus  20  with reference to  FIG. 4 .  FIG. 4  shows the configuration of the disk array apparatus  20  configured in the enclosure  22 .  
         [0052]     The hard disk units  46 F on the front side are connected to the back panel  34  by connectors  54 , whereas the hard disk units  46 B on the back side are connected to the back panel  36  by connectors  54 . On the other hand, the I/F units  48  and  49  and the power supply units  50  and  52  are each connected to the back panel  38  by connectors  56 . There is connected to the back panel  38 , the back panel  34  via a first flat cable  58  and the back panel  36  via a second flat cable  60 . Each of the flat cables  58  and  60  is provided along the bottom surface of the enclosure  22 .  
         [0053]     On the other hand, there is connected to the I/F units  48  and  49 , a host computer  66  through external input/output cables  62  and  64 , respectively. Therefore, the I/F unit  48  mediates between the hard disk units  46 F on the front side and the host computer  66  and takes charge of delivery and reception of data, whereas the I/F unit  49  mediates between the hard disk units  46 B on the back side and the host computer  66  and takes charge of delivery and reception of data. Each of the power supply units  50  and  52  is individually supplied with power externally through external input/output cables  68  and  70 .  
         [0054]     In such a configuration, the power supply unit  50  takes charge of supplying power to the hard disk units  46 F on the front side, whereas the power supply unit  52  takes charge of supplying power to the hard disk units  46 B on the back side. Therefore, the hard disk units  46 F on the front side are supplied with I/F signal and power through the flat cable  58 , whereas the hard disk units  46 B on the back side are supplied with I/F signal and power through the flat cable  60 .  
         [0055]     Description will be given next of rack mounting of the enclosures  22  with reference to  FIG. 5 .  FIG. 5  shows rack mounting of the enclosures  22 .  
         [0056]     This rack  72  is 36U in height, allowing for the 36 enclosures  22  as stated above to be attached. In each of the enclosures  22 , there are mounted the hard disk units  46 F,  46 B and so on shown in  FIG. 3 .  
         [0057]     When the hard disk units  46 F and  46 B shown in  FIG. 3  are provided in the enclosures  22 , letting the storage capacity of each of the hard disk units  46 F and  46 B be 73 GB and the total number of the hard disk units  46 F and  46 B mounted in each of the enclosures  22  be 20, then the total storage capacity M 3  is: 
 
 M   3 =20×73 [GB]×36=52,560 [GB]
 
 In this case, the storage capacity per 1U or M 3 /36 is: 
 
 M   3 /36=20×73 [GB]=1,460 [GB]
 
 Hence, by using the 2.5-inch hard disk units  46 F and  46 F, it is possible to achieve a value similar to in the case that the 3.5-inch hard disk units  8  ( FIG. 2 ) are used. 
 
         [0058]     Description will be given next of extraction of the hard disk units  46 F on the side of the back panel  34  with reference to  FIG. 6 .  FIG. 6  shows extraction of the hard disk unit  46 F from the enclosure  22  on the rack  72 .  
         [0059]     On the front side of the rack  72 , there are set up posts  74  and  76  for supporting the enclosures  22 , with the flange portions  26  of the enclosures  22  attached to each of the posts  74  and  76  by locking screws  78  so as to be attachable and detachable. On the front surface portion of each of the enclosures  22 , there is formed the opening portion  24 , thus allowing for extraction of the hard disk units  46 F on the front side from the opening portion  24  in the direction of an arrow A and replacement thereof.  
         [0060]     Description will be given next of extraction of the enclosures  22  with reference to  FIGS. 7 and 8 .  FIG. 7  shows the enclosure  22  as extracted from the rack  72 , whereas  FIG. 8  shows the fixing mechanism of the movable frame portion.  
         [0061]     The enclosures  22  mounted in the rack  72  are supported on the rack  72  by the slide rail  32  of the sliding mechanism  30  so as to be freely slidable, thus allowing the enclosures  22  to be pulled out toward front (in the direction of an arrow B) of the rack  72  by removing the locking screws  78 .  
         [0062]     On the top portion of the enclosures  22 , there are provided a cover portion  80  for covering the hard disk units  46 F on the front side and a movable frame portion  82  for mounting the hard disk units  46 B on the back side. The movable frame portion  82  is configured, as mentioned later, so that it can open/close during attachment/detachment and replacement of the hard disk units  46 B on the back side, and there is attached to the movable frame portion  82 , an operation unit  86  for operating a fixing mechanism  84  ( FIG. 8 ). Through operations of the operation unit  86 , the movable frame portion  82  is detached from the enclosure  22 , thus opening the movable frame portion  82 .  
         [0063]     Description will be given next of a rotational motion mechanism and the fixing mechanism  84  of the movable frame portion  82  with reference to FIGS.  9  to  12 .  FIG. 9  is a view showing the movable frame portion  82  as closed,  FIG. 10  is a view showing the movable frame portion  82  as open,  FIG. 11  is an exploded perspective view showing the rotational motion mechanism, and  FIG. 12  is an exploded perspective view showing the fixing mechanism  84 .  
         [0064]     On the side surface portions of the enclosure  22 , there is provided a rotational motion mechanism  88  that supports the movable frame portion  82  so as to be rotationally movable. That is, there are set up a pair of bearing plates  90  as supporting members, with the movable frame portion  82  supported on the bearing plate  90  via a rotation supporting shaft  92  so as to be rotationally movable. The rotation supporting shaft  92  is attached to the upper corner portion on the back side of the movable frame portion  82 . In the movable frame portion  82 , there are mounted the hard disk units  46 B on the back side and the back panel  36  described earlier. A gear mechanism  94  mediates between the bearing plate  90  and the movable frame portion  82 , and the gear mechanism  94  is made up of a rotationally movable first gear  98  attached to a supporting shaft  96  of the bearing plate  90  and a fan-shaped second gear  100  attached to the movable frame portion  82  using the rotation supporting shaft  92  as the rotation center, with the gears  98  and  100  meshing with each other. The second gear  100  is larger in diameter than the first gear  98 , restricting the open/close range and rotational motion angle of the movable frame portion  82 .  
         [0065]     In the gear mechanism  94 , there are provided a spring mechanism  102  as a mechanism for imparting a force in the opening direction to the movable frame portion  82  and a coil spring  104  wound around the rotation supporting shaft  92 , with one end thereof supported by the side of the movable frame portion  82  and the other end supported by a fixed portion  106  protruding from the enclosure  22 . In the condition shown in  FIG. 9 , the coil spring  104  is in a compressed state, with its restoration force acting between the gear  100  of the movable frame portion  82  and the enclosure  22 .  
         [0066]     On both side portions on the front of the movable frame portion  82 , there is provided the already-described fixing mechanism  84 , and in the present embodiment, there are provided a U-shaped expansion/contraction portion  108  formed with a spring material and having the front end side that is a free end, a claw portion  110  as a locking portion protruded from the middle portion of the expansion/contraction portion  108  and the operation unit  86  for stretching or shrinking the expansion/contraction portion  108 . In the enclosure  22 , there is provided a catching portion  112  for engagement with the claw portion  110 . When the claw portion  110  is locked to the catching portion  112 , the movable frame portion  82  is fixed and restricted within the enclosure  22 , and when the claw portion  110  is unlocked from the catching portion  112  as a result of stretching or shrinkage of the expansion/contraction portion  108 , the movable frame portion  82  moves rotationally to become open through the action of the restoration force of the coil spring  104 , as shown in  FIG. 10 .  
         [0067]     In such a configuration, as the enclosure  22  is pulled out from the rack  72  and the claw portion  110  is unlocked from the catching portion  112  through operation of the operation unit  86  of the fixing mechanism  84 , the movable frame portion  82  moves rotationally under the restoration force of the coil spring  104  centering around the rotation supporting shaft  92  and becomes upwardly open from the cover portion  80  covering the hard disk units  46 F on the front side, as shown in  FIG. 13 . In this condition, the hard disk units  46 B are extracted from the movable frame portion  82 , allowing for easy replacement thereof.  
         [0068]     Although a considerably large restoration force from the coil spring  104  acts on the side of the movable frame portion  82  at the time of rotational motion of the movable frame portion  82 , a reaction force acts to counter the restoration force due to meshing of the gears  98  and  100  and a gear ratio of the two gears, thus alleviating the force of rotational motion of the movable frame portion  82 . This renders the rotational motion of the movable frame portion  82  gentle, thus alleviating the impact on the hard disk units  46 B mounted in the movable frame portion  82 . At the same time, the impact is alleviated on the enclosure  22 . It is possible therefore to protect the hard disk units  46 B and others from damage due to the impact.  
         [0069]     Description will be given next of the sliding mechanism  30  with reference to  FIG. 14 .  FIG. 14  shows an example of the sliding mechanism  30 .  
         [0070]     In the sliding mechanism  30 , since the slide rail  32  attached to the enclosure  22  is made of a channel material having a C-shaped cross section, there is attached to the side of the rack  72 , a guide rail portion  114  corresponding with the slide rail  32 . In the guide rail portion  114 , there are attached rollers  118  and  120 , that correspond with groove portions  116  formed at upper and lower portions of the slide rail  32 , so as to be rotationally movable by supporting shafts  122 . In such a configuration, the slide rail  32  and the guide rail portion  114  come in contact with each other via the rollers  118  and  120 , thus allowing smooth sliding of the enclosure  22  on the rack  72 .  
         [0071]     Description will be made of other embodiments.  
         [0072]     (1). While in the above embodiment, description was made taking the disk array apparatus  20  as an example, the present invention is applicable to electronic equipment equipped with a plurality of apparatus units and is not limited to the disk array apparatus  20 .  
         [0073]     (2) While description was made of the fixing mechanism  84  configured using a U-shaped spring material, the fixing mechanism  84  may be alternatively configured using a material other than a spring material so long as the fixing mechanism  84  can restrict the movable frame portion  82  within the enclosure  22 , and so the fixing mechanism  84  is not limited to a configuration using a spring material.  
         [0074]     While the most preferred embodiments of the present invention have been described hereinabove, the present invention is not limited to the above embodiments, and it is a matter of course that various variations and modifications can be made by those skilled in the art within the scope of the claims without departing from the spirit of the invention disclosed herein, and needless to say, the variations and modifications are also included in the scope of the present invention.  
         [0075]     The entire disclosure of Japanese Patent Application No. 2004-145299 including specification, claims, drawings and summary are incorporated herein by reference in its entirety.