Abstract:
Provided is a cooling method for realizing efficient cooling of a storage apparatus with an airflow separation structure. This storage apparatus has a plurality of cooling areas formed in the cabinet; an external air introduction/discharge device for directing external air to the respective cooling areas, and thereafter discharging the external air from a discharge area of the cabinet outside the cabinet; and an external air guidance area for guiding the external air that passed through each of the cooling areas to the discharge area; wherein the external air guidance area is configured so that the external air that passed through one cooling area will not get mixed with the external air that passed through another cooling area.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application relates to and claims priority from Japanese Patent Application No. 2006-083445, filed on Mar. 24, 2006, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present invention generally relates to a high-density mounting storage apparatus housing numerous memory mediums in a cabinet, and in particular relates to a storage apparatus having a configuration for improving the cooling capability in the cabinet. 
     Generally speaking, a part of the power supplied to a hard disk drive in an electronic apparatus is converted into frictional heat caused by the rotation of the hard disk or resistance heat of an electronic circuit. With a storage apparatus having a plurality of hard disk drives arranged in an array, the denser these hard disk drives are mounted, the higher the heating value. Thus, while the storage apparatus is being operated, it is necessary to cool the hard disk drives and electronic circuits in the storage apparatus. 
     In recent years, as represented by a large storage apparatus configured with a RAID (Redundant Array of Independent Disks) system, for instance, the storage capacity of storage apparatuses is of an increasing trend. In other words, the number of hard disk drives mounted on the storage apparatus is increasing, which means that the mounting density of the hard disk drives is increasing. 
     As a result of this high-density mounting, the power consumption and heating value of storage apparatuses are ever increasing. As a measure against such heat generation, although a fan for introducing external air into the storage apparatus is being enlarged, resistance against the circulation of external air in the storage apparatus is significant due to the high-density mounting of the hard disk drives, and an effect of sufficiently cooling the inside of the storage apparatus has not yet been achieved. Thus, there is no choice but to enlarge the fan even further, which results in distracting noise caused by the fan, and the electricity consumption for operating the fan will also increase. 
     Conventionally, as a magnetic disk device having this kind of cooling system, as described in Japanese Patent Laid-Open Publication No. H8-273345, proposed is a magnetic disk device configured by including in a single apparatus cabinet a plurality of magnetic disk drives for magnetically storing information, a control circuit board mounted with a control circuit for controlling such magnetic disk drives, and a ventilation means for cooling the magnetic disk drives and control circuit board with air cooling, wherein the magnetic disk drives, control circuit board and ventilation means are retained in a frame to configure a single disk box, and a plurality of such disk boxes are housed in a single apparatus cabinet. 
     Further, Japanese Patent Laid-Open Publication No. 2005-19562 describes a storage apparatus including a ventilation unit provided on a ceiling of a cabinet for ventilating the interior and exterior of the cabinet, a hollow duct having two opening surfaces and arranged in a first housing unit for housing a first electronics device housing box formed at a level on the side near the ceiling so that the first opening surface faces the ventilation unit, a second opening surface faces a second housing unit for housing a second electronics device housing box formed at a level on the side far from the ceiling, air inside the second electronics device housing box housed in the second housing unit is discharged from the ventilation unit outside the cabinet through the interior of the duct, and air in the first electronics device housing box housed in the first housing unit is discharged from the ventilation unit outside the cabinet along the outer wall surface of the duct. 
     SUMMARY 
     Nevertheless, although Japanese Patent Laid-Open Publication No. H8-273345 proposes providing a ventilation means to each disk box for cooling each disk unit, no consideration is given to streamlining the exhaust air or miniaturizing the fan. 
     Further, with Japanese Patent Laid-Open Publication No. 2005-19562, since the fan located at the upper row of the first housing unit also has the role of transporting both the exhaust air from the second housing unit and the exhaust air from the first housing unit outside the cabinet, the amount of external air to be discharged will increase. Thus, it is difficult for external air in the cabinet in a location away from the fan to be discharged outside the cabinet, and, as result, external air tends to remain in the cabinet, and the cooling capability will deteriorate thereby. 
     Moreover, since the position of the external air that cooled the first housing unit and the external air that cooled the second housing unit flow in the same duct, the position of such former external air and latter external air entering the duct are different; that is, because the external air flowing in the first housing unit enters the duct from midway and the external air flowing in the second housing unit enters from the starting end of the duct, there is a problem in that the circulation of external air in the duct will become off balance, and the cooling capability will deteriorate. In order to avoid this problem, it is necessary to enlarge the fan even more. 
     The present invention was devised in view of the foregoing problems, and an object thereof is to inhibit the noise generated by the fan upon cooling the storage apparatus, and inhibit the electricity consumption required for such cooling. 
     In order to achieve the foregoing object, the present invention is characterized in that the flow of external air for cooling the first housing unit and the flow of external air for cooling the second housing unit are not mixed in the storage apparatus. 
     In other words, the present invention provides a storage apparatus having in a cabinet, and arranged in one direction, a memory medium housing unit for storing a plurality of memory mediums, a control unit for performing data I/O processing to the memory mediums in response to a data I/O request from an upper-level host system, and a power supply unit for supplying power to the memory medium housing unit and the control unit, including: a plurality of cooling areas formed in the cabinet; an external air introduction/discharge device for directing external air to the respective cooling areas, and thereafter discharging the external air from a discharge area of the cabinet outside the cabinet; and an external air guidance area for guiding the external air that passed through each of the cooling areas to the discharge area; wherein the external air guidance area is configured so that the external air that passed through one cooling area will not get mixed with the external air that passed through another cooling area. 
     According to the present invention, it is possible to inhibit the noise generated by the fan upon cooling the storage apparatus, and inhibit the electricity consumption required for such cooling. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing the overall storage apparatus; 
         FIG. 2  is a perspective view showing a state where the respective units are housed in a cabinet  200  of the storage apparatus  100 ; 
         FIG. 3  is a perspective view of the overall storage apparatus for showing the cooling system of the storage apparatus; 
         FIG. 4  is a diagram showing a state where a decorative panel  230  is disposed around the cabinet  200 ; 
         FIG. 5  is a diagram showing a configuration for independently forming, in essence, a guidance route of the external air formed in the storage apparatus for each cooling area; 
         FIG. 6A  and  FIG. 6B  are diagrams showing a state where intake air  216  from the upper row of the cabinet is discharged outside the cabinet as exhaust air  218 ; 
         FIG. 7A  and  FIG. 7B  are diagrams showing a state where external air  220  introduced from the middle and lower parts of the cabinet  200  is discharged outside the storage apparatus; 
         FIG. 8A  and  FIG. 8B  are diagrams showing a state where a panel  330  is provided to the frame  210 B at the front side and back side of the structure; 
         FIG. 9  is a diagram showing a state where external air  220  introduced from the middle and lower parts of the cabinet  200  is discharged outside the storage apparatus; 
         FIG. 10A  to  FIG. 10E  are diagrams showing the configuration of the structure; 
         FIG. 11A  to  FIG. 11D  are diagrams showing the measurement of the structure; 
         FIG. 12A  to  FIG. 12B  are diagrams showing a modified example of the structure; 
         FIG. 13A  to  FIG. 13E  are diagrams showing a modified example of the structure; 
         FIG. 14  is a diagram showing a modified example of the structure; and 
         FIG. 15  is a diagram showing a modified example of the structure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention are now explained with reference to the attached drawings.  FIG. 1  is a perspective view showing the overall storage apparatus. As shown in  FIG. 1 , the storage apparatus  100  is configured by housing, in a cabinet  200  forming a large rectangular shape, a DC power supply  600 , a battery  800 , an LG box (control unit)  400  and an HDD box  300  from the ground plane side of the cabinet toward the top side of the cabinet in that order. 
     An upper-level system not shown (a host system for example) is connected to the storage apparatus illustrated in  FIG. 1 , and data to be accessed by the host system is stored in the hard disk drive in the HDD box  300 . Each HDD box  300  has a plurality of hard disk drives  300 A arranged in an array. The LG box  400  has a control circuit for controlling the input and output of data between the host system and storage apparatus. The DC power supply  600  converts AC power into DC power, and supplies DC power to the LG box and HDD box. The battery  800  is a standby power supply device. 
       FIG. 2  is a perspective view showing a state where the respective units are housed in the cabinet  200  of the storage apparatus  100 . The foregoing HDD box  300  is housed in the upper row of the storage apparatus  10 . The hard disk drive  300 A in the HDD box  300  is insertably and removably housed in the HDD box. Electric fans  500  are provided at the top face of the storage apparatus. These electric fans guide the external air from outside the cabinet toward the center of the cabinet via the HDD box, and discharge this external air from the top of the storage apparatus. 
     A total of 64 disk drives  310  are loaded in an array in the HDD box  300 ; 4 rows in the direction of gravitational force, and 16 rows in a direction perpendicular to the vertical direction. Incidentally, a plurality of frames are assembled to form a rectangular shape so as to configure the overall cabinet  200 , and the upper row, middle row and lower row of the cabinet are formed with partition frames  201 ,  202 . The HDD box  300  is supported above the partition frame  201 . The control unit  400  is being supported and fixed by the partition frame  202  in the middle row formed between the partition frame  201  and partition frame  202 . Further, the DC power supply  600 , battery  800  and AC box  700  are housed in the lower row formed between the partition frames and the frame  203  at the bottom of the cabinet. 
     The LG box (control unit)  400  has a plurality of logical substrates  430  with a control circuit formed thereon. The logical substrate  430  is insertably and removably housed in the LG box. The logical substrate  430  includes a channel adapter for performing communication between the storage apparatus  100  and information processing device in order to input and output data, a disk adapter for performing I/O processing of data stored in the disk drive  300 A, and a cache memory for storing data sent to and received from the information processing device. Electric fans  410  for drawing in external air from the outside to inside of the cabinet are provided to the top face of the LG box  400 . These electric fans guide external air into the cabinet via the power supply unit and LG box, and then discharge such external air outside the cabinet. 
     The battery  800 , AC box  700  and DC power supply  600  are housed inside the lower row of the cabinet  200 . These integrally form the power supply unit of the storage apparatus. By disposing the heavy power supply unit in the lower row of the storage apparatus  100 , it is possible to stabilize the storage apparatus upon grounding the storage apparatus. Incidentally, as shown in  FIG. 1 , an operational input unit  100 A is provided to the front side of the storage apparatus. 
     The DC power supply  600  converts AC power into DC power, and supplies DC power to the LG box  400  and disk drive  310 . The battery  800  supplies backup powder to the respective components inside the storage apparatus  100  during a blackout or failure in the DC power supply  600 . The AC box  700  is an intake of AC power to the storage apparatus  100 , and functions as a breaker. AC power introduced into the AC box  700  is supplied to the DC power supply  600 . The significant heating value generated by the power supply unit in the lower row of the storage is cooled by the external air supplied into the cabinet with the electric fans  410 . Incidentally, as shown in  FIG. 2 , a pair of HDD boxes  300 , LG boxes  400  and power supply units are respectively disposed and housed in the storage apparatus; one from the front side and one from the back side of the storage apparatus. 
       FIG. 3  is a perspective view of the overall storage apparatus for showing the cooling system of the storage apparatus. The cooling area of the storage apparatus is broadly separated into two sections; in other words, the cooling area is configured from an area  212  for cooling the HDD box  300 , and an area  214  for cooling the LG box  400  and power supply unit  410 A. The electric fan  500  aspirates the external air  216  from the outside to inside of the cabinet via the HDD box. This external air is discharged outside the storage apparatus  100  as exhaust air  218  by the electric fan  500 . The external air  216  passes through the vicinity of the hard disk drive while flowing from the outside to inside of the cabinet so as to cool the hard disk drive. 
     Although not directly shown in  FIG. 3 , the electric fan  410  explained with reference to  FIG. 2  aspirates the external air  220  from the outside to inside of the cabinet via the LG box  400  and power supply unit  410 A, and this external air rises in the cabinet, passes through a space  222  formed between the HDD box and side face of the cabinet, and is discharged outside the cabinet as exhaust air  224 . The external air guidance route or external air guidance area from the external air being introduced as intake air  216  and thereafter discharged outside the cabinet as exhaust air  218 , and the route or area from the external air being introduced as intake air  220  and thereafter discharged outside the cabinet as exhaust air  224  from the left and right side faces of the cabinet are formed so that the external air of the former and external air of the latter do not get mixed. In other words, it is possible to substantially avoid the external air  220  from becoming the external air for cooling the HDD box. 
     Incidentally, as shown in  FIG. 4 , a decorative panel  230  is provided around the cabinet  200 . The decorative panel, although not shown, is provided with a plurality of openings for introducing external air. A ventilation space is formed between the decorative panel  230  and cabinet  200 . Moreover, in  FIG. 3 , the external air is aspirated into the storage apparatus from the front side, back side, right side and left side of the storage apparatus. 
     Next, the configuration for independently forming, in essence, a guidance route of the external air formed in the storage apparatus for each of the two cooling areas is explained.  FIG. 5  is a perspective view showing this configuration. A pair of HDD boxes  300  is housed inside the storage apparatus respectively from the front side and back side of the storage apparatus. Provided between the pair of HDD boxes  300  is a structure  210  substantially differentiating the introduction route of the intake air  220  passing through the cabinet as shown in  FIG. 3  from the introduction route of the external air  216  passing through the cabinet. As a result of this structure, the introduction route of external air in the cabinet will be as shown in  FIGS. 6A and 6B , and  FIGS. 7A and 7B . In  FIGS. 6A and 6B , although this partially overlaps with the explanation of  FIG. 3 , intake air  216  enters the structure  210  from the front side and left/right sides of the HDD box, and is discharged outside the cabinet as exhaust air  218  with the fan  500  in the exhaust air area of the storage apparatus. In  FIG. 7 , external air  200  aspirated from the periphery of the middle row and lower row of the cabinet  200 , without passing through the inside of the structure  210 , rises between the left/right sides on the outside of the structure  210  and the cabinet; that is, between the cabinet and the housing area of the HDD box, and is discharged outside the storage apparatus as exhaust air  224 . 
     Next, returning to  FIG. 5  to explain the structure  210  in detail, the structure  210  is formed in a rectangular shape where the planar surface and inside are opened. The bottom face of the structure  210  is shielded so that the external air  220  (refer to  FIG. 7 ) will not enter the structure. This is the same for the left and right sides of the structure  210 . As shown in  FIG. 8A , the structure  210  is configured by including a bottom face  210 A, left and right side faces  210 C, and a frame  210 B for forming the overall structure in a rectangular shape. At the front side and back side of the structure, a panel  330  is fixed to the frame  210 B. This panel, as shown in  FIG. 5 , is facing the HDD box. A plurality of openings  330 A are formed on the panel  330  to allow external air to enter into the structure  210 . The density of forming such openings is formed so as to increase toward the lower end of the structure  210  (toward the bottom face of the storage apparatus) (refer to  FIG. 8B ). 
     This is in order to deal with the situation where the suction power for introducing external air into the structure  210  may weaken as it becomes farther from the fan  500 . Outside air  216  shown in  FIG. 3  is guided into the structure  210  via the openings  330 A, and, as shown in  FIG. 9 , the external air  220  rises in the cabinet along the left and right sides  210 C of the structure, and does not rise through the structure  210 . Therefore, the structure  210  is able to separate the area to which the intake air  216  is directed and the area to which the intake air  220  is directed. The fan  500  will only require a capacity sufficient in aspirating and discharging the intake air  216 , and the fan  410  will only require a capacity sufficient in aspirating and discharging the intake air  220 . 
     In other words, the structure  210  is configured such as the upper part thereof is formed in an open box shape, a fan  500  is provided to the upper part of the structure, and a fan  410  is also provided facing downward toward the bottom of the structure  10  so as to separate the external air. Therefore, the noise generated during the operation of the fan can be reduced, and it is possible to discharge external air efficiently. Incidentally, since the structure  210  was not provided conventionally, the intake air  220  was mixed with the intake air  216  in the cabinet, and the mixed external air was collectively discharged with the fan  500 . Thus, there was no choice but to enlarge the fan  500 . As a result, the power consumption and noise of the fan would increase. Further, although the enlargement of the axis for rotating the wings of the fan would shield the air passage, by miniaturizing the fan, such fan can be installed in accordance with the area of the passage. 
     As shown in  FIG. 10A , inclined faces  213 A and  213 B are formed from the front side end  211 A and back side end  211 B of the bottom face  210 A toward the center of the structure  210  at the left and right sides of the bottom face  210 A of the structure  210 . Moreover, a ridge line  213 D is formed from the center  215 A of the bottom face  210 A so as to connect the inclined faces  213 A and  213 B and an intersection  213 C. As a result of the inclined faces  213 A,  213 B and the ridge line  213 D, a pair of semitriangular cone-shaped concave portions  217  is formed from the center of the structure to the left and right sides, respectively. Outside air  220  is force fed to the structure  210  side with the fan  400 , thereafter comes in contact with the bottom face  210 A of the structure  210 , and directed to the left and right side faces  210 C of the structure along the concave portion  217 . With respect to the width of this concave portion, since the concave portion is of a triangular cone shape, the width of the concave portion gradually becomes larger from the center of the structure toward the left and right sides, and external air  220  is directed smoothly to from the center of the structure to the left and right sides. In other words, external air  220  is directed smoothly from the center of the structure to the left and right sides with the pair of concave portions  217  formed from the center of the structure toward the left and right sides. That is to say, the structure  210  is configured to have a concave portion so that the exhaust air from the LG box flows toward a direction in which the HDD box is not installed; that is, in a direction toward the side face. Further, the inclined faces  213 A,  213 B are able to direct external air from the front side and back side of the structure to the center of the structure. The flow of this external air is shown in  FIG. 9 . 
       FIG. 11A to 11D  show the measurements of the structure. One side on the front side of the bottom face of the structure is L, one side on the side face is D, and the height of the structure is H. The intermediate point of the front side end  211 A and back side end  211 B of the bottom face of the structure is  211 D. The length from  211 A to  211 D is d, the length from  211 D to the center  215 A of the bottom face  210 A is I, and the length from  211 D to  213 C is h. Then, the structure is formed to satisfy the relationship of:
 
0 ≦L− 2 I/L 2
 
0≦ d≦D/ 2
 
0≦h≦H
 
     This structure is formed from metal, resin or Styrofoam. 
     In the concave portion  217  formed at the bottom face of the structure  210 , as shown in  FIG. 12A , so as long as the relationship of 0≦−2I≦L/2 is satisfied, the size of L−2I may be larger than 0. In other words, the apex of the semitriangular concave portion  217  does not have to be formed at the single point of  215 A, and there may be several apexes as shown with  215 B and  215 C, and the space between such apexes may be distant. 
     Further, as shown in  FIG. 12B ,  211 C may be provided at a position that is more inside than the front side end  211 A of the bottom face, and  211 E may be provided at a position that is more inside than the back side end  211 B of the bottom face, respectively, and the concave portion  217  may be formed from such  211 C and  211 D toward the center of the structure. Here, when the length from  211 A to  211 C is a, the length from  211 E to  211 B is b, length a or b from  211 C or  211 E to  211 D may be formed shorter than one side D/2 on the side of the bottom face of the structure  210  so that a, b&lt;D/2. 
     Incidentally, the ridge line  213 D formed from the center  215 A of the bottom face  210 A so as to connect the inclined faces  213 A,  213 B and the intersection  213 C, for instance, as shown in  FIG. 13 , may also be a curved line. Here, one side on the front side of the bottom face of the structure is L, one side on the side face is D, and the height of the structure is H. The intermediate point of the front side end  211 A and back side end  211 B of the bottom face of the structure is  211 D. The length from  211 A to  211 D is d, the length from  211 D to the center  215 A of the bottom face  210 A is I, and the length from  211 D to  213 C is h. Then, the structure is formed to satisfy the relationship of:
 
0 ≦L− 2 I≦L/ 2
 
0 ≦d≦D/ 2
 
0≦h≦H
 
     Further, when the angles shown in  FIG. 13B to 13E  are set to α, β, γ, σ, ε, the structure is formed to satisfy the relationship of 0°&lt;α, β, γ, ζ, σ, ε&lt; 90 °. 
     Moreover, the shape of the concave portion  217  formed on the bottom face of the structure  210  does not necessarily have to be a shape similar to a cone shape, and, as shown in  FIG. 14 , may be configured by combining various shapes such as an oval shape or circular shape. Further still, the ridge line  213 D formed so as to connect the inclined faces  213 A,  213 B and the intersection  213 C does not necessarily have to be a straight line, and may also be a flux line, curved line, or formed in a staircase pattern. Furthermore, the ridge line  213 D does not necessarily have to be a symmetrical line profile. 
     In addition, the shape of the cut area of the concave portion  217  appearing on the side face  210 C of the structure  210  does not necessarily have to be triangular, and, as shown in  FIG. 15 , may be a semi oval shape or circular shape, and there is no particular limitation in the shape of the cut area so as long as the concave portion has some kind of depression. Moreover, the cut area does not necessarily have to take on a symmetrical shape on both side faces. 
     The embodiments of the present invention were described above to facilitate the understanding of the present invention, and are not intended to limit the interpretation of the present invention in any way. The present invention may be modified or improved without deviating from the gist thereof, and equivalents of the present invention are also included therein.