JP2009093225A - Storage control device, method, program, and storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the processing delay of a JOB whose processing priority is high even when I/O processing with which data with a large capacity is transferred is executed. <P>SOLUTION: A cache use condition storage means 21 prestores cache use conditions. An I/O determination means 22 determines whether or not cache use conditions stored in a cache use condition storage means 21 are satisfied with information acquired from I/O commands 31 and 41. When it is determined that the cache use conditions are satisfied with the I/O determination means 22, a transfer path control means 23 transfers data through a cache memory 11 between host servers 30 and 40 and a logical disk 12, and when it is determined that the cache use conditions are not satisfied with the I/O determination means 22, data are directly transferred between the host servers 30 and 40 and the logical disk 12 without using the cache memory 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a storage control device or the like that uses a cache memory to write or read data to or from a storage medium in response to an I / O command from a host server.

  A cache memory is a high-speed memory placed between a high-speed processing device such as a CPU and a low-speed storage device. A general storage device is equipped with a cache memory that holds data in order to process data reading and writing at high speed (see, for example, Patent Document 1).

  In addition, backup means copying data and storing it. For example, data and programs stored in a computer or server are stored in another storage medium in case of damage or computer virus infection. That is.

JP 2004-252526 A

  However, in a general storage apparatus, when an I / O process such as a backup job in which a large amount of data is transferred is executed, there is a problem that a processing delay of a job with a high processing priority occurs. In other words, when a data backup job or the like is executed, the cache utilization rate of the storage device increases due to the I / O processing of the data backup job, the amount of cache available for the online job decreases, and the online job processing delay occurs. was there.

  Accordingly, an object of the present invention is to provide a storage control device or the like that can suppress a processing delay of a JOB having a high processing priority even when an I / O processing for transferring a large amount of data is executed. is there.

  A storage control apparatus according to the present invention is used in a storage apparatus having a storage medium and a cache memory, and transfers data between the host server and the storage medium in response to an I / O command from the host server. It is. The storage control apparatus according to the present invention includes a cache usage condition storage unit that stores cache usage conditions in advance, and a cache usage condition in which information obtained from the I / O command is stored in the cache usage condition storage unit. I / O determination means for determining whether or not the data satisfies the condition, and if the I / O determination means determines that the cache usage condition is satisfied, data is transferred between the host server and the storage medium via the cache memory. And when the I / O determination means determines that the cache usage condition is not satisfied, the transfer path control means transfers the data directly between the host server and the storage medium without going through the cache memory. And.

  A storage apparatus according to the present invention includes the storage control apparatus according to the present invention, the storage medium, and the cache memory.

  A storage control method according to the present invention is used in a storage apparatus including a storage medium and a cache memory, and transfers data between the host server and the storage medium in response to an I / O command from the host server. It is. The storage control method according to the present invention stores cache usage conditions in advance, determines whether or not the information obtained from the I / O command satisfies the cache usage conditions, and sets the cache usage conditions. When satisfying, the data is transferred between the host server and the storage medium via the cache memory, and when the cache usage condition is not satisfied, the cache memory is transferred between the host server and the storage medium. It is characterized in that data is directly transferred without going through.

  A storage control program according to the present invention is used in a storage apparatus including a storage medium and a cache memory, and transfers data between the host server and the storage medium in response to an I / O command from the host server. belongs to. The storage control program according to the present invention includes a cache usage condition storage unit that stores cache usage conditions in advance, and a cache usage condition in which information obtained from the I / O command is stored in the cache usage condition storage unit. I / O determining means for determining whether or not the condition is satisfied, and when the I / O determining means determines that the cache usage condition is satisfied, the cache memory is interposed between the host server and the storage medium. And transferring the data directly between the host server and the storage medium without going through the cache memory when the I / O determination means determines that the cache usage condition is not satisfied. The computer functions as path control means.

  According to the present invention, if the information obtained from the I / O command does not satisfy the cache use condition, the data is transferred directly without going through the cache memory, so that the large-capacity data transfer is performed. Since the data can be directly transferred without going through the cache memory when the data is received, the processing delay of JOB having a high processing priority can be suppressed.

  FIG. 1 is a block diagram showing an embodiment of a storage control device and a storage device according to the present invention. Hereinafter, description will be given based on this drawing.

  The storage device 10 of this embodiment includes a storage control device 20, a cache memory 11, a logical disk 12 as a storage medium, and the like. The storage device 10 is connected to the two host servers 30 and 40 via the switch device 13. The storage control device 20 according to the present embodiment transfers data between the host servers 30 and 40 and the logical disk 12 in response to I / O commands 31 and 41 from the host servers 30 and 40, and uses a cache. Condition storage means 21, I / O determination means 22, transfer path control means 23, and the like are provided.

  The cache use condition storage means 21 stores the cache use condition in advance. The I / O determination unit 22 determines whether or not the information obtained from the I / O commands 31 and 41 satisfies the cache usage condition stored in the cache usage condition storage unit 21. When the I / O determination unit 22 determines that the cache usage condition is satisfied, the transfer path control unit 23 transfers data between the host servers 30 and 40 and the logical disk 12 via the cache memory 11, and If the / O determination unit 22 determines that the cache usage condition is not satisfied, the data is directly transferred between the host servers 30 and 40 and the logical disk 12 without passing through the cache memory 11.

  The I / O determination means 22 determines which of the host servers 30 and 40 is based on a unique address of a host bus adapter (HBA) 32 or 42 provided for each of the host servers 30 and 40. To do. The cache use condition storage unit 21 stores the cache use condition for each of the host servers 30 and 40. The I / O determination unit 22 determines whether or not the cache usage condition is satisfied for each of the host servers 30 and 40.

  Here, the host bus adapters 32 and 42 are interface controllers for connecting a host server and peripheral devices. In the case of SCSI (Small Computer System Interface), both “SCSI adapter” and “SCSI controller” are used. In the case of fiber channel, it is also called “fiber channel adapter”. A 64-bit unique address called WWN (World Wide Name) is assigned to the host bus adapters 32 and 42. There are two WWNs, a port name and a node name, and WWN usually refers to a port name.

  The logical disk 12 is a magnetic disk. However, the storage medium is not limited to a magnetic disk but may be an optical disk or a semiconductor memory.

  FIG. 2 is a block diagram showing an example of the configuration of the transfer path control means in FIG. Hereinafter, a description will be given based on FIG. 1 and FIG.

  The transfer path control unit 23 includes a cache data transfer path 24, a host data transfer path 25, a disk control unit 26, and the like. The cache data transfer path 24 is used when transferring data via the cache memory 11. The host data transfer path 25 is used when transferring data directly without going through the cache memory 11. The disk control unit 26 reads and writes data from and to the logical disk 12 and determines one of the cache data transfer path 24 and the host data transfer path 25 based on the determination result of the I / O determination unit 22. Used to transfer data.

  The cache data transfer path 24 and the host data transfer path 25 are connected by a bus, and to which path data transfer is performed is determined by an address output by the disk control means 26. When the data is read from the logical disk 12, the transfer path can be switched by instructing the read address to the disk control means 26. These paths can be realized by a general bus such as PCI (Peripheral Component Interconnect).

  FIG. 3 is a block diagram illustrating an example of a hardware configuration of the storage control apparatus in FIG. Hereinafter, a description will be given based on FIGS. 1 and 3.

  The storage control device 20 has a general microcomputer including a CPU 51, a RAM 52, a ROM 53, an input / output interface 54, and the like. The input / output interface 54 is connected to the cache memory 11, the logical disk 12, the switch device 13, and the like. A program and data for causing the microcomputer to function as the cache use condition storage unit 21, the I / O determination unit 22 and the transfer path control unit 23 are stored in the RAM 52. The CPU 51 takes out the instruction sequences stored in the RAM 52 one by one, interprets them and executes them. Each unit of the storage control device 20 can be configured only by hardware without using software, or can be configured by firmware.

  Next, operations and effects of the storage control device 20 and the storage device 10 of this embodiment will be described with reference to FIG.

  When large-capacity data transfer such as the backup JOB 34 is performed via the cache memory 11, a large part of the cache memory 11 is thereby occupied, and processing delay occurs in the online JOBs 33, 43 having high priority. Therefore, for example, it is determined in advance that “online JOB satisfies the cache usage condition” and backup JOB “does not satisfy the cache usage condition”, and the information obtained from the I / O commands 31 and 41 satisfies the cache usage condition. If not, the data is transferred directly without going through the cache memory 11. Therefore, according to the storage control device 20, when an I / O command for transferring a large amount of data is received, the data is directly transferred without going through the cache memory 11, so that the processing delay of JOB with high processing priority is increased. Can be suppressed.

  In addition, since the storage apparatus 10 includes the storage control apparatus 20, if the information obtained from the I / O commands 31 and 41 does not satisfy the cache usage condition, the data is directly transmitted without going through the cache memory 11. By transferring, when I / O commands 31 and 41 for transferring a large amount of data are received, the data can be transferred directly without going through the cache memory 11, thereby reducing the processing delay of JOB having a high processing priority. Can be suppressed.

  FIG. 4 is a chart showing a first example of a table (cache use condition) stored by the cache use condition storage means in FIG. FIG. 5 is a flowchart showing a first example of the operation of the storage control apparatus of this embodiment. Hereinafter, a first example of the operation of the storage control apparatus according to this embodiment will be described with reference to FIG. 1, FIG. 4, and FIG.

  The cache use condition storage means 21 in this example stores “cache use maximum I / O transfer length” as the cache use condition. If the I / O transfer length included in the I / O commands 31 and 41 does not exceed the “maximum cache usage I / O transfer length” stored in the cache usage condition storage unit 21, the I / O determination unit 22 If it is determined that the use condition is satisfied and the I / O transfer length included in the I / O commands 31 and 41 exceeds the “maximum cache use I / O transfer length” stored in the cache use condition storage unit 21, the cache use is performed. It is determined that the condition is not satisfied. In a general disk interface such as SCSI, I / O commands 31 and 41 are issued before data transfer. Since the I / O transfer length is included in the I / O commands 31 and 41, the I / O determination means 22 can determine the I / O transfer length before starting the transfer.

  Referring to FIG. 1, the storage device 10 is connected to the host server 0 (host server 30) and the host server 1 (host server 40) via the switch device 13, and includes a cache use condition storage unit 21, an I / O determination unit. 22, transfer path control means 23, cache memory 11, logical disk 12, cache data transfer path 24, host data transfer path 25, and the like.

  The cache use condition storage unit 21 has a function of storing the set “cache use maximum I / O transfer length” for each WWN in the format shown in FIG. The “cache maximum I / O transfer length” for each host bus adapter 32, 42 may be set by a command from the host servers 30, 40 or an external terminal that can be connected to the storage apparatus 10. In FIG. 4, “HBA0... 32K bytes” means that the data related to HBA0 passes through the cache memory 11 if the transfer length is 32K bytes or less and does not pass the cache memory 11 if the transfer length exceeds 32K bytes. Similarly, “HBA1... No Limit” means that all data related to HBA1 passes through the cache memory 11.

  The I / O determination means 22 determines the issue source WWN of the received I / O command and the transfer length of the received I / O command, and these are stored in the “cache use maximum I” stored in the cache use condition storage means 21. / O transfer length ".

  The transfer path control means 23 has a function of switching the data read from the logical disk 12 to either the cache data transfer path 24 or the host data transfer path 25. The cache data transfer path 24 has a function of transferring data read from the logical disk 12 to the cache memory 11. The host data transfer path 25 has a function of directly transferring data read from the logical disk 12 to the host servers 30 and 40.

  Next, description will be made mainly with reference to the flowchart of FIG. First, when receiving the I / O commands 31 and 41 from the host servers 30 and 40, the I / O determination means 22 determines the WWN of the I / O issuer and the I / O transfer length (step 101). Subsequently, the I / O determination unit 22 acquires the “cache use maximum I / O transfer length” of the I / O issue source WWN from the cache use condition storage unit 21 (step 102). Subsequently, the I / O determination unit 22 compares the received I / O transfer length with the “cache use maximum I / O transfer length” acquired from the cache use condition storage unit 21 (step 103). If the received I / O transfer length exceeds the “cache use maximum I / O transfer length” as a result of the comparison, the I / O determination unit 22 uses the host data transfer path 25 for the transfer path control unit 23. To notify the data transfer (step 104). As a result of the comparison, if the received I / O transfer length is equal to or smaller than the “cache use maximum I / O transfer length”, the I / O determination unit 22 sends the cache data transfer path 24 to the transfer path control unit 23. Is used to notify data transfer (step 105). The transfer path control unit 23 performs cache transfer on / off switching for each I / O transfer length set for each of the host servers 30 and 40 by performing data transfer using the path notified from the I / O determination unit 22. It becomes possible to do.

  As described above, the storage control device 20 including the cache use condition storage unit 21, the I / O determination unit 22, the transfer path control unit 23, and the like has the following functions. 1. A function that switches cache use on and off according to the set transfer length. 2. A function of changing the transfer length of cache use on / off switching by setting the transfer length of cache use on / off switching for each WWN of the HBA.

  That is, the storage control device 20 executes data backup JOB or the like by switching on / off of cache use in the I / O processing of the storage device 10 according to the I / O transfer length set for each of the host servers 30 and 40. The processing delay of the online JOB that can occur is suppressed. “Maximum cache usage I / O transfer length” in which cache use is turned on and off for each host server, taking advantage of the fact that the I / O transfer length of data backup jobs is generally larger than the I / O transfer length of online jobs. And the processing delay of the online JOB generated by the large capacity data I / O such as the data backup JOB is suppressed. In other words, in the case of an I / O exceeding the set “maximum cache use I / O transfer length”, the I / O process can be performed without using the cache memory 11 of the storage apparatus 10, and can be used in an online JOB. It is possible to secure the cache amount, and it is possible to suppress the processing delay of the online job when executing the backup job.

  FIG. 5 is a chart showing a second example of a table (cache use condition) stored by the cache use condition storage unit in FIG. FIG. 6 is a flowchart showing a second example of the operation of the storage control apparatus of this embodiment. Hereinafter, a second example of the operation of the storage control apparatus according to this embodiment will be described with reference to FIG. 1, FIG. 6, and FIG.

  In the first example, the I / O transfer length is used as a reference for performing on / off switching of cache use, but in this example, the sequential number of sequential access I / O is used. That is, when the sequential access I / O number is a certain number or more, it is determined that the backup job has a large data capacity. Note that “sequential access” is one of the methods for reading and writing data, and means a method for sequentially accessing from the top. On the other hand, a method of directly accessing a place where reading or writing is desired is called “random access”. In sequential access, reading and writing are sequentially performed from the head position where data is recorded. For this reason, even when it is desired to search for necessary data, it takes time compared to random access because it is read sequentially from the top. On the other hand, when all data is required, sequential access is faster because continuous access is possible.

  The cache use condition storage means 21 in this example stores the maximum cache use number for the number of consecutive I / O sequential accesses as the cache use condition. The I / O determination means 22 determines whether or not the I / O command is an I / O sequential access, and the cache use condition storage means 21 stores the number of consecutive I / O sequential accesses. If the maximum number is not exceeded, it is determined that the cache usage condition is satisfied, and if the number of consecutive I / O sequential accesses exceeds the maximum cache usage number stored in the cache usage condition storage unit 21, it is determined that the cache usage condition is not satisfied. To do.

  That is, the cache use condition storage means 21 is referred to as a sequential access count threshold (hereinafter referred to as “cache use maximum sequential access I / O continuous count”) that can use the cache memory 11 for each WWN in the format shown in FIG. ) Is remembered. The I / O determination means 22 has a function for determining whether or not the received I / O command is a sequential access, and the number of consecutive sequential accesses for each I / O issue source WWN in the format shown in FIG. 6 [1]. Has a function to memorize.

  In FIG. 6 [1], “HBA 0... 5” indicates that the sequential number of sequential accesses related to HBA 0 is currently “5”. Similarly, “HBA1... 10” indicates that the sequential number of sequential accesses related to HBA1 is currently “10”. In FIG. 6 [2], “HBA 0... 20” means that if the number of sequential accesses related to HBA 0 is “20” or less, the cache memory 11 is passed and if it exceeds “20”, the cache memory 11 is not passed. It is. Similarly, “HBA1... No Limit” means that all data related to HBA1 passes through the cache memory 11.

  Next, description will be made mainly with reference to the flowchart of FIG. First, when receiving the I / O commands 31 and 41 from the host servers 30 and 40, the I / O determination unit 22 determines the WWN of the I / O issuer (step 201), and the received I / O command is It is determined whether or not the access is sequential (step 202). When the access is not sequential, the I / O determination unit 22 resets the sequential access I / O counter (step 206) and instructs the transfer path control unit 23 to perform data transfer using the cache memory 11 ( Step 207).

  On the other hand, if it is a sequential access, the I / O determination means 22 increments the sequential access I / O counter by 1 (step 203). Subsequently, the I / O determination unit 22 compares the value of the sequential access counter with the value set in the cache use condition storage unit 21. (Step 204) When the value of the sequential access counter is equal to or smaller than the “maximum number of sequential sequential I / O accesses using cache”, the I / O determination unit 22 performs transfer so as to perform data transfer using the cache memory 11. The path control means 23 is instructed (step 207). When the value of the sequential access counter exceeds “the maximum number of sequential sequential I / O accesses using the cache”, the I / O determination unit 22 performs the transfer path control unit 23 so as to perform the data transfer without using the cache memory 11. (Step 205).

  By performing the above operation, it is possible to realize the cache use ON / OFF switching by the “cache use maximum sequential access I / O continuous number” set for each of the host servers 30 and 40.

  Next, an embodiment of the storage control method according to the present invention will be described. The storage control method of this embodiment is the operation itself of the storage control apparatus of FIG. Therefore, description will be made based on FIG.

  The storage control method according to the present embodiment is used in the storage apparatus 10 including the logical disk 12 and the cache memory 11, and is logically connected to the host servers 30 and 40 according to the I / O commands 31 and 41 from the host servers 30 and 40. Data is transferred to and from the disk 12. The storage control method of this embodiment stores the cache usage conditions in advance, determines whether the information obtained from the I / O commands 31 and 41 satisfies the cache usage conditions, and sets the cache usage conditions. When satisfied, the data is transferred between the host servers 30 and 40 and the logical disk 12 via the cache memory 11, and when the cache usage condition is not satisfied, between the host servers 30 and 40 and the logical disk 12. Data is directly transferred without going through the cache memory 11. Each component can be embodied in the same manner as the storage control device in FIG.

  According to the storage control method of the present embodiment, if the information obtained from the I / O commands 31 and 41 does not satisfy the cache usage condition, the data is transferred directly without going through the cache memory 11, thereby allowing a large capacity. When the I / O commands 31 and 41 for performing data transfer are received, the data can be transferred directly without going through the cache memory 11, so that it is possible to suppress the processing delay of JOB having a high processing priority.

  Next, an embodiment of a storage control program according to the present invention will be described. The storage control program of this embodiment is for causing a computer to function each unit of the storage control apparatus of FIG. Therefore, description will be made based on FIG.

  The storage control program according to the present embodiment is used in the storage apparatus 10 including the logical disk 12 and the cache memory 11, and is logically connected to the host servers 30 and 40 according to the I / O commands 31 and 41 from the host servers 30 and 40. This is for transferring data to and from the disk 12. The storage control program of this embodiment is characterized by causing a computer (see FIG. 3) to function as the cache usage condition storage unit 21, the I / O determination unit 22, and the transfer path control unit 23. The cache use condition storage means 21 stores the cache use condition in advance. The I / O determination unit 22 determines whether or not the information obtained from the I / O commands 31 and 41 satisfies the cache usage condition stored in the cache usage condition storage unit 21. When the I / O determination unit 22 determines that the cache usage condition is satisfied, the transfer path control unit 23 transfers data between the host servers 30 and 40 and the logical disk 12 via the cache memory 11, and If the / O determination unit 22 determines that the cache usage condition is not satisfied, the data is directly transferred between the host servers 30 and 40 and the logical disk 12 without passing through the cache memory 11. Each component can be embodied in the same manner as the storage control device in FIG.

  According to the storage control program of the present embodiment, if the information obtained from the I / O commands 31 and 41 does not satisfy the cache use condition, the data is transferred directly without going through the cache memory 11, thereby When the I / O commands 31 and 41 for performing data transfer are received, the data can be transferred directly without going through the cache memory 11, so that it is possible to suppress the processing delay of JOB having a high processing priority.

  Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art may be made to the configuration and details of the present invention. Further, the present invention includes a combination of some or all of the configurations of the above-described embodiments as appropriate. In the examples of FIGS. 5 and 7, the case where data is read from the storage medium has been described. However, the case where data is written to the storage medium is also included in the present invention since the data transfer direction is only reversed. The number of host servers connected to the storage apparatus is not limited to two, and may be one or three or more.

1 is a block diagram showing an embodiment of a storage control device and a storage device according to the present invention. FIG. It is a block diagram which shows an example of a structure of the transfer path control means in FIG. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the storage control device in FIG. 1. It is a chart which shows the 1st example of the table (cache usage condition) which the cache usage condition storage means in FIG. 1 stores. 3 is a flowchart showing a first example of the operation of the storage control device of FIG. 1. It is a chart which shows the 2nd example of the table (cache usage condition) which the cache usage condition storage means in FIG. 1 stores. 6 is a flowchart showing a second example of the operation of the storage control device of FIG. 1.

Explanation of symbols

10 storage device 11 cache memory 12 logical disk (storage medium)
20 Storage Controller 21 Cache Usage Condition Storage Unit 22 I / O Determination Unit 23 Transfer Path Control Unit 24 Cache Data Transfer Path 25 Host Data Transfer Path 30 Host Server (Host Server 0)
32 Host bus adapter (HBA0)
40 Host server (Host server 1)
42 Host bus adapter (HBA1)

Claims (12)

In a storage control device that is used in a storage device including a storage medium and a cache memory, and transfers data between the host server and the storage medium in response to an I / O command from the host server,
Cache usage condition storage means for storing cache usage conditions in advance;
I / O determination means for determining whether information obtained from the I / O command satisfies a cache usage condition stored in the cache usage condition storage means;
When the I / O determination means determines that the cache usage condition is satisfied, data is transferred between the host server and the storage medium via the cache memory, and the I / O determination means determines the cache. When it is determined that the use condition is not satisfied, transfer path control means for directly transferring data between the host server and the storage medium without going through the cache memory;
A storage control device comprising: The host server is plural,
The cache use condition storage means stores the cache use condition for each of the plurality of host servers,
The I / O determination means determines whether or not the cache usage condition is satisfied for each of the plurality of host servers;
The storage control device according to claim 1. The I / O determination means determines which host server is based on a unique address of a host bus adapter provided for each of the plurality of host servers.
The storage control device according to claim 2. The cache use condition storage means stores a cache use maximum I / O transfer length as the cache use condition,
The I / O determination means determines the cache usage condition if the I / O transfer length included in the I / O command does not exceed the maximum cache usage I / O transfer length stored in the cache usage condition storage means. If the I / O transfer length included in the I / O command exceeds the maximum cache use I / O transfer length stored in the cache use condition storage unit, the cache use condition is not satisfied. To
The storage control device according to claim 1, wherein the storage control device is a storage control device. The cache usage condition storage means stores the maximum number of cache usages of consecutive I / O sequential accesses as the cache usage condition,
The I / O determination means determines whether or not the I / O command is an I / O sequential access, and a cache in which the number of consecutive I / O sequential accesses is stored in the cache use condition storage means. If the maximum usage number is not exceeded, it is determined that the cache usage condition is satisfied, and if the number of consecutive I / O sequential accesses exceeds the maximum cache usage number stored in the cache usage condition storage unit, the cache usage condition is determined. Judge that it does not meet,
The storage control device according to claim 1, wherein the storage control device is a storage control device. The storage control device according to any one of claims 1 to 5, the storage medium, the cache memory,
A storage apparatus comprising: In a storage control method for transferring data between the host server and the storage medium in response to an I / O command from the host server, used in a storage device including a storage medium and a cache memory,
Store cache usage conditions in advance,
Determining whether information obtained from the I / O command satisfies the cache usage condition;
When the cache usage condition is satisfied, data is transferred between the host server and the storage medium via the cache memory. When the cache usage condition is not satisfied, the host server and the storage medium Directly transferring data without going through the cache memory,
And a storage control method. The host server is plural,
Storing the cache usage condition for each of the plurality of host servers;
For each of the plurality of host servers, it is determined whether information obtained from the I / O command satisfies the cache usage condition.
The storage control method according to claim 7. When determining whether the information obtained from the I / O command satisfies the cache usage condition for each of the plurality of host servers,
Determining which host server is based on a unique address of a host bus adapter provided for each of the plurality of host servers;
The storage control method according to claim 8. A storage control program for use in a storage device having a storage medium and a cache memory, for transferring data between the host server and the storage medium in response to an I / O command from the host server,
Cache usage condition storage means for storing cache usage conditions in advance;
I / O determination means for determining whether or not information obtained from the I / O command satisfies a cache usage condition stored in the cache usage condition storage means; and
When the I / O determination means determines that the cache usage condition is satisfied, data is transferred between the host server and the storage medium via the cache memory, and the I / O determination means determines the cache. A transfer path control means for transferring data directly between the host server and the storage medium without going through the cache memory when it is determined that the use condition is not satisfied;
A storage control program for causing a computer to function as The host server is plural,
The cache use condition storage means stores the cache use condition for each of the plurality of host servers,
The I / O determination means determines whether or not the cache usage condition is satisfied for each of the plurality of host servers;
The storage control program according to claim 10, wherein: The I / O determination means determines which host server is based on a unique address of a host bus adapter provided for each of the plurality of host servers.
The storage control program according to claim 11, wherein:

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