JP7381122B2 - Disk array system, method for disk array system, and computer program for disk array system - Google Patents

Description

The present invention relates to a disk array system, a method for the disk array system, and a program for the disk array system.

2. Description of the Related Art Disk array systems having a RAID (Redundancy Array of Independent Disk) configuration using a plurality of physical disks are widely used in servers constituting computer systems to ensure reliability against disk failures. In addition, a disk array system is provided in which by installing a spare disk for a physical disk in preparation for a physical disk failure, the disk array system can automatically switch to the spare disk in the event of a physical disk failure and maintain redundancy. However, because it is a spare in case of failure, it occupies the disk slot of the disk array device even though it is not normally used, reducing the maximum disk capacity that the disk array device can provide. It turns out. Furthermore, preparing a spare physical disk in case of failure even though it is not available during normal times also increases costs.

Patent Document 1 discloses that in order to efficiently operate a spare physical disk for a RAID configuration, a spare disk system unit is provided, and when a spare disk allocation request is received from any server, the spare disk system A system for creating partitions on disks in a unit and allocating spare disks is disclosed.

Japanese Patent Application Publication No. 2010-9476

Even though the system disclosed in Patent Document 1 allows for efficient use of spare disks, it is still necessary to prepare spare disks. Therefore, there are problems in that an additional disk slot is required to accommodate the disk, and the maximum disk capacity that the disk array system can provide is reduced.

In order to solve the above problems, the present invention aims to provide a disk array system, a method for the disk array system, and a program for the disk array system.

According to a first aspect of the present invention, a disk array system is a system that configures RAID (Redundancy Array of Independent Disks) in a disk array, in which multiple logical disks utilize the entire capacity of multiple physical disks. Each file system is configured using the entire capacity of each logical disk, and when one of the plurality of physical disks fails, the file system is configured on a logical disk that does not include the failed physical disk . The present invention includes a control means for securing a substitute area for the failed physical disk for a file system built on a logical disk including the failed physical disk, by using free space in the failed file system.

According to a second aspect of the present invention, a method for a disk array system is a system that configures RAID in a disk array, wherein a plurality of logical disks utilizes the entire capacity of a plurality of physical disks. In a system in which each file system is configured using the full capacity of each logical disk, when one of the plurality of physical disks fails, a computer including the failed physical disk Find free space in a file system built on a logical disk that does not exist, and use the free space to create a replacement area for the failed physical disk for the file system built on a logical disk that includes the failed physical disk. secure.

Further, according to a third aspect of the present invention, a computer program for a disk array system is a system that configures RAID in a disk array, wherein a plurality of logical disks utilizes the entire capacity of a plurality of physical disks. For a system in which each file system is configured using the full capacity of each logical disk , when one of the plurality of physical disks fails, the logical disk that does not include the failed physical disk Find the free space in the file system built on the disk, and use the free space to secure an alternative area for the failed physical disk for the file system built on the logical disk that includes the failed physical disk. make a computer do something.

According to the present invention, it is possible to provide a disk array system that does not reduce the maximum disk capacity that the disk array system can provide.

FIG. 1 is a block diagram showing the configuration of a disk array system in an embodiment of the present invention. FIG. 3 is a diagram showing an example of a table for managing each physical disk, logical disk, and file system in an embodiment of the present invention. 1 is a diagram showing an example of a hardware configuration in which a server and a disk array control device in a disk array system according to an embodiment of the present invention are realized by a computer device including a processor. 7 is a flowchart showing the operation of the input/output control unit of the disk array control device in one embodiment of the present invention when a failure of a physical disk is detected. FIG. 3 is a diagram showing an example of alternative area reservation request information in an embodiment of the present invention. 7 is a flowchart showing the operation of an input/output agent that receives an alternative area reservation request in an embodiment of the present invention. FIG. 3 is a diagram showing an example of an alternative area management table regarding an alternative area of a failed physical disk in an embodiment of the present invention. 7 is a flowchart showing the operation of an input/output control unit that receives a result in response to an alternative area reservation request in an embodiment of the present invention. 7 is a flowchart showing the operation of the input/output control unit after a maintenance worker replaces a physical disk with an operable physical disk according to an embodiment of the present invention. 7 is a flowchart showing the operation of an input/output agent that receives an alternative area deletion request from an input/output control unit in an embodiment of the present invention. 1 is a diagram showing a minimum configuration diagram of a disk array system according to an embodiment of the present invention. FIG.

In the disk array system of this embodiment, in order to make maximum use of the disk capacity, a logical disk composed of multiple physical disks is configured to utilize the entire capacity of the physical disks, regardless of the type of RAID. . Further, the disk array system configures a file system on a logical disk using the entire capacity of the logical disk configured using physical disks. That is, in the disk array system of this embodiment, the entire capacity of the physical disks is always in use. By the way, when thinking from the perspective of a file system, the amount of file system usage depends on the user, and there is a possibility that the file system actually has sufficient free space.

Therefore, the disk array system in this embodiment does not use a spare disk as an alternative area for a failed physical disk, but instead uses a file system built on another logical disk that does not include the failed physical disk in its configuration. Secure a file for a replacement area for the failed physical disk and use this secured area. In this way, spare disks are no longer required, and disk slots are no longer occupied by spare disks, allowing users of disk array systems to maximize the capacity of all physical disks installed in the disk array system. You will be able to do this.

In an environment where a disk array device such as a SAN (Storage Array Network) storage is connected to a server, the server constructs and manages the file system in the disk array device, and the file system cannot be interpreted by the disk array device alone. Therefore, in an environment where a disk array device such as a SAN (storage) is connected to a server, the disk array device and the server are each implemented so that they work together. The array device and server are sometimes collectively referred to as a "disk array system."

The file secured as a replacement area for a failed physical disk will be very large because it will be the same size as the failed physical disk, but it is not necessarily necessary to use a single file as a replacement area. The disk array system in this embodiment can be distributed over file systems on multiple logical disks as long as the condition that an alternative area is placed on a file system built on a logical disk that does not include a failed physical disk is satisfied. By arranging a substitute area, it can be used as a substitute area for the failed physical disk.

Note that the purpose of the disk array system in this embodiment is to maintain logical disk redundancy during a temporary period until maintenance personnel replace a failed disk with a new disk and recover from the failure. , it will not work if files corresponding to the capacity of the failed disk cannot be secured on the file system.

Hereinafter, a disk array system according to an embodiment of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a disk array system according to the same embodiment. The disk array system 1 is composed of a server 101 and a disk array device 104. This embodiment assumes SAN storage and will be described as an example in which the server 101 and the disk array device 104 are connected via a network, but the present invention is not limited to this. The server 101 uses the logical disks of the disk array device 104 to construct, manage, and utilize a file system on the logical disks. The disk array device 104 is a device with a RAID configuration using a plurality of physical disks.

An operating system (OS) 102 is installed on the server 101. Furthermore, the operating system 102 is equipped with an input/output agent 103 for securing and managing an alternative area for a failed physical disk in the disk array device 104.

The disk array device 104 is composed of a disk array control device 105 and a plurality of physical disks. The example in FIG. 1 shows an example composed of six physical disks 108 to 113. Control firmware (control FW) 106 is installed in the disk array control device 105. Furthermore, inside the control firmware 106, an input/output control unit 107 is installed to cope with the failure of the logical disk.

The disk array device 104 configures three logical disks each using two physical disks. The logical disk 114 is configured in RAID1 using the physical disk 108 and the physical disk 109. The logical disk 114 is configured using all the capacity of the physical disks 108 and 109, and makes maximum use of the capacity of the physical disks. Similarly, the logical disk 115 is composed of a physical disk 110 and a physical disk 111, and the logical disk 116 is composed of a physical disk 112 and a physical disk 113. In this embodiment, in order to simplify the explanation, a configuration is used in which there are six physical disks and three logical disks, but the configuration is not limited to this and there may be more. Further, regarding the RAID type, although the RAID 1 configuration is configured with two physical disks, other RAID types such as RAID 5 or RAID 6, which use three or more physical disks, may be used.

Each file system is built by the operating system 102 on a respective logical disk. Note that the type of file system is not particularly limited. In the example of FIG. 1, the file system 117 is constructed using the entire capacity of the logical disk 114, making the most of the capacity of the logical disk 114. Similarly, file system 118 and file system 119 are constructed on logical disk 115 and logical disk 116, respectively.

Next, an example of a table for managing each physical disk, logical disk, and file system will be explained using FIG. 2. Table 301 in FIG. 2 is an example of a table for managing physical disks. As shown in the table 301, the physical disks 108 to 113 each have a capacity of 300 GB. Table 302 is an example of a table for managing logical disks. As shown in the table 302, the logical disks 114 to 116 are all RAID 1, and each capacity is 300 GB. In reality, the capacity may be slightly reduced due to the need for a data area for management, but in this example, this point will be ignored for ease of understanding. Note that the tables 301 and 302 are managed by the disk array control device 105.

Table 303 is an example of a table for managing a file system. As for file systems 117 to 119, as shown in table 303, each capacity is assumed to be 300 GB. The actual capacity of the file system will also be slightly smaller, but this will be ignored in this example. It is assumed that 150 Gbytes, 50 Gbytes, and 110 Gbytes of each of the file systems 117, 118, and 119 are in use by a user using the disk array device 104, respectively. Further, each file system 117, 118, 119 is provided with a setting for a margin capacity when creating an alternative area. This creates an alternative area in the file system, leaving free space to ensure that the remaining capacity in the file system is not used up until the system maintainer replaces the failed physical disk. This is the capacity and is managed by the input/output agent 103. Here, each is assumed to be 50 GB. Note that the margin capacity at the time of creating an alternative area may be set to a different value for each file system, taking into consideration the rate of increase in the usage capacity of each file system, the expected period from physical disk failure to replacement, and the like. Note that each of the tables 301 to 303 shown in FIG. 2 is updated each time there is a change.

FIG. 3 is a diagram showing an example of a hardware configuration in which the server 101 and the disk array control device 105 in the disk array system 1 of the present disclosure are realized by the computer device 2 including a processor. As shown in FIG. 3, the computer device 2 includes a CPU (Central Processing Unit) 201, a memory such as a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, and a storage device such as a hard disk that stores a program 204. 205 included. Further, the computer device 2 includes a communication I/F (Interface) 208 for connection to a communication network 213 and an input/output interface 211 for inputting and outputting data to and from a peripheral device 214 . Further, the computer device 2 connects each device configuring the computer device 2 to an input device 209 and an output device 210 provided inside or outside the computer device 2 via a bus 212.

The CPU 201 operates an operating system to control the entire computer device 2 that implements the server 101 and the disk array control device 105. Further, the CPU 201 reads programs and data from a recording medium 206 attached to, for example, a drive device 207 to a memory.

The recording medium 206 is, for example, an optical disk, a flexible disk, a magneto-optical disk, an external hard disk, or a semiconductor memory. Some recording media are non-volatile storage devices and programs are recorded thereon. Further, the program may be downloaded from an external computer (not shown) connected to a communication network.

The input device 209 is realized by, for example, a mouse, a keyboard, a built-in key button, etc., and is used for input operations. The input device 209 is not limited to a mouse, a keyboard, or a built-in key button, but may be a touch panel, for example. The output device 210 is implemented as a display, for example, and is used to confirm the output.

Note that the server 101 and the disk array control device 105 of the present disclosure do not need to have all the configurations shown in FIG. 3. For example, in the server 101 or the disk array control device 105, if the drive device 207 is not required for its function, it can be omitted. Further, in FIG. 3, the input/output agent 103 and the input/output control unit 107 are realized by codes executable by the processor (CPU) 201, and are loaded into the RAM at the time of execution. Furthermore, the functions of the input/output agent 103 and the input/output control unit 107 can be changed by changing the executable code.

The operation of the disk array system 1 will be explained below using FIGS. 4 to 9. Further, in the following explanation, the operation will be explained by taking as an example a case where the physical disk 108 in FIG. 1 fails. FIG. 4 is a flowchart showing the operation when the input/output control unit 107 of the disk array control device 105 detects a failure of a physical disk. The operation shown in FIG. 4 starts when the input/output control unit 107 detects a failure in the physical disk 108. First, the input/output control unit 107 performs processing to logically disconnect the failed physical disk 108 (S11). Subsequently, the input/output control unit 107 checks the status of the logical disk 114 whose component is the failed physical disk 108 (S12). Specifically, the input/output control unit 107 confirms from the table 302 in FIG. 2 that the RAID type of the logical disk 114 whose component is the failed physical disk 108 is the RAID1 configuration. The input/output control unit 107 checks whether the physical disk 109, which is another physical disk constituting the RAID 1 logical disk 114, is normal. If the physical disk 109 is normal (S12: Yes), the input/output control unit 107 determines that the logical disk 114 can continue to operate, and proceeds to step S14. On the other hand, if the physical disk 109 is not normal (S12: No), the input/output control unit 107 determines that the logical disk 114 cannot continue to operate, and performs processing to logically disconnect the logical disk 114 ( S13), the logical disk 114 is deemed unusable and the process ends.

If the logical disk 114 can continue to operate, the input/output control unit 107 creates alternative area reservation request information (S14). FIG. 5 shows an example of alternative area reservation request information. In the alternative area reservation request information 501, the physical disk name is the name of the failed physical disk. Here, the physical disk 108 is assumed. Note that the physical disk name is a name or value that uniquely identifies a physical disk in the disk array system 1. The physical disk capacity is the capacity of the failed physical disk. The input/output control unit 107 specifies the capacity of the failed physical disk 108 as "300 GB" from the table 301 of FIG. 2 managed by the disk array device 104, and records it in the alternative area reservation request information 501. The logical disk name is the name of the logical disk configured including the failed physical disk. This is information necessary for the input/output agent of the server 101 to exclude a replacement disk from being reserved as a replacement area for a failed physical disk. Here, it is the logical disk 114. After completing the creation of the alternative area reservation request information 501, the input/output control unit 107 issues an alternative area reservation request to the input/output agent 103 using the created information (S14).

Next, the operation of the input/output agent 103 that receives the alternative area reservation request will be explained using FIG. 6. The operation shown in FIG. 6 is started when the input/output agent 103 receives an alternative area reservation request. First, the input/output agent 103 identifies the target logical disk based on the received alternative area reservation request, and also confirms the capacity to be secured (300 GB in the example) (S21). Next, the input/output agent 103 checks the status of all file systems 117 to 119 mounted by the server 101 using the table 303 in FIG. 2 or the like (S22).

Depending on the results of the confirmation in steps S21 and S22, the input/output agent 103 uses the file stems built on logical disks other than the logical disk that included the failed physical disk to perform It is determined whether it is possible to secure an alternative area for the physical disk that has been used (S23). The capacity to be secured is 300 GB since it is the physical disk capacity of the alternative area reservation request information 501. The candidate file system to be secured is a file system on a logical disk other than the logical disk indicated by the alternative area reservation request information 501. Therefore, in this example, the file systems 118 and 119 are other than the file system 117 built on the logical disk 114. In order to determine whether it is possible to secure a replacement area for the failed physical disk in step S23, the input/output agent 103 first makes an inquiry to the operating system 102, A result is received indicating that the file systems constructed above are file systems 118 to 119 and can be used. Next, the input/output agent 103 checks the table 303 that it manages. That is, the input/output agent 103 confirms that the free capacity of the file system 118 is 250 GB, and the margin capacity at the time of creating the alternative area is 50 GB. Then, the input/output agent 103 reserves 200 GB, leaving 50 GB from the file system 118, as an alternative area. At this point, an additional 100 GB (=300 G-200 G) is required as an alternative area, so the input/output agent 103 subsequently checks the file system 119, which is another file system. Since the file system 119 has a free capacity of 200 GB and a margin capacity of 50 GB when creating an alternative area, the remaining 100 GB can be secured. At this point, the input/output agent 103 determines that the required 300 GB can be secured.

In the judgment in step S23, if it is determined that the alternative area cannot be secured, that is, the capacity is insufficient (S23: No), the input/output agent 103 notifies the input/output control unit 107 that the reservation has failed, Finish the process.

On the other hand, if it is determined that the reservation is successful (S23: Yes), the input/output agent 103 creates an alternative area management table 701 regarding the alternative area of the failed physical disk 108, as shown in FIG. 7 (S24). In the alternative area management table 701, the input/output agent 103 records that 200 GB is reserved as an alternative area in the file system 118 and 100 GB is reserved as an alternative area in the file system 119, and the capacity of each file system is recorded in the alternative area management table 701. Performs processing to create an empty file. An image of the alternative area of the failed physical disk 108 is as shown in 702 in FIG. In this example, the file created on the file system 118 will be responsible for the first 200 GB, and the file created on the file system 119 will be responsible for the 201 GB to 300 GB. Finally, the input/output agent 103 notifies the input/output control unit 107 that the alternative area has been successfully secured, and ends the process.

Next, the operation of the input/output control unit 107 that receives the result of the alternative area reservation request will be described using FIG. 8. The operation shown in FIG. 8 is started when the input/output control unit 107 receives the result of the alternative area reservation request. The input/output control unit 107 determines whether the received result is a success or a failure (S31). If it is a failure (S31: No), the input/output control unit 107 ends the process without performing any further processing. If successful (S31: Yes), the input/output control unit 107 creates/updates the alternative area in use list (S32). Here, the input/output control unit 107 performs processing to add the physical disk 108 to the alternative area in use list. Note that the alternative area in use list is a list showing a list of failed physical disks for which alternative areas are valid. Thereafter, the input/output control unit 107 rebuilds the logical disk 114 using the secured alternative area in place of the failed physical disk (S33). Here, the rebuild is a process of copying the contents of the non-faulty physical disk 109 that constitutes the logical disk 114 to an alternative area. Note that since the alternative area is secured on the file system and the file system is managed by the server 101, the input/output control unit 107 sends a copy request to the alternative area for rebuilding to the input/output area in the server 101. This will be done for the agent 103. By completing the rebuild, the logical disk 114 is restored to a redundant state. From now on, the input/output control unit 107 issues an input/output request to the physical disk 108 to maintain the RAID configuration not to the physical disk 108 but to the input/output agent 103 by referring to the alternative area in use list. Become. When the input/output agent 103 receives a read/write request from the input/output control unit 107, it refers to the alternative area management table 701 and reads/writes the corresponding file.

The operation of the input/output control unit 107 after a maintenance worker replaces the failed physical disk with a normal physical disk in a state where the physical disk 108 has failed will be described with reference to FIG. The operation of the flowchart shown in FIG. 9 starts when the replacement of the physical disk 108 with a normal physical disk is completed. The input/output control unit 107 executes a rebuild by copying the contents of the non-faulty physical disk 109 that constitutes the logical disk 114 to the replaced physical disk 108 (S41). After the rebuild is completed, the input/output control unit 107 deletes the physical disk 108 from the alternate area in use list, notifies the input/output agent 103 of the alternate area deletion request (S42), and ends the process.

The operation of the input/output agent 103 that receives the alternative area deletion request from the input/output control unit 107 will be explained using FIG. 10. The flowchart shown in FIG. 10 starts when the input/output agent 103 receives an alternative area deletion request. Based on the alternative area deletion request, the input/output agent 103 refers to the alternative area management table 701 and deletes the files on the file systems 118 and 119 secured as alternative areas. Further, the input/output agent 103 deletes the table related to the physical disk 108 from the alternative area management table (S51), and ends the process.

Note that if the physical disk 109 fails while the physical disk 108 is being replaced with an alternative area, the alternative area of the physical disk 109 will be secured by the same operation as described above. However, the input/output agent 103 selects a file system that does not overlap with the file system being used as a substitute area for the physical disk 108, and secures a substitute area for the physical disk 109 on the selected file system. In this example, since the file systems 118 to 119 are already in use, an alternative area for the physical disk 109 cannot be secured, but if there is another file system, an attempt is made to secure an alternative area for the physical disk 109 from that. In this way, even when a plurality of physical disks constituting a logical disk are switched to an alternative area, the disk array system 1 operates without problems as long as the alternative area can be secured. Note that when a failed physical disk is replaced with a new physical disk, the rebuild copy source may be an alternative area rather than a normal physical disk within the same logical disk.

As described above, in the disk array system 1, there is no need to prepare a spare disk, and when a disk failure occurs, there is no need to prepare another storage device until maintenance personnel replace the failed disk. Redundancy can be maintained.

In addition, since the disk slots in the disk array device 104 are not occupied by spare disks, it is possible to allocate the disk slots to normal disks, which maximizes the disk capacity that can be provided by the disk array device 104. can be increased.

In addition, compared to a system that uses cache memory as an alternative area, since cache memory is not used as an alternative area, there is no performance degradation to logical disks unrelated to the failed disk.

Note that as long as the storage is recognizable by the server 101, even if it is another storage other than the disk array device 104, it can be used as an alternative area.

FIG. 11 is a diagram showing a minimum configuration diagram of the disk array system 1 according to an embodiment of the present invention. The disk array system 1 includes a control section 11. The disk array system 1 is a system that configures RAID, and when a physical disk fails, the control unit 11 uses free space in a file system built on a logical disk that does not include the physical disk to A process is performed to secure an alternative area for the failed physical disk in the file system.

Note that by recording a program for realizing the functions of the processing unit shown in FIG. In step 1, a replacement area may be secured for the failed disk. Note that the "computer system" herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer system" includes a WWW system equipped with a home page providing environment (or display environment). Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" refers to volatile memory (RAM) inside a computer system that serves as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. This also includes programs that are retained for a certain period of time.

Further, the program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in a transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Moreover, the above program may be for realizing a part of the above-mentioned functions. Furthermore, it may be a so-called difference file (difference program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

1 Disk array system 101 Server 102 Operating system 103 I/O agent 104 Disk array device 105 Disk array control device 106 Control firmware 107 I/O control unit 108-113 Physical disks 114-116 Logical disks 117-119 File system

Claims (10)

A system that configures RAID (Redundancy Array of Independent Disks) in a disk array,
The plurality of logical disks are configured using the entire capacity of the plurality of physical disks, each file system is configured using the entire capacity of the respective logical disk,
When one of the physical disks among the plurality of physical disks fails, the free space in the file system built on the logical disk that does not include the failed physical disk is used to create a logical disk that includes the failed physical disk. A disk array system comprising: a control means for securing an alternative area for the failed physical disk for a constructed file system. When the file system on one logical disk that does not include the failed physical disk is unable to secure an alternative area for the failed physical disk, the control means controls the file system on a plurality of logical disks that do not include the failed physical disk. The disk array system according to claim 1, wherein the alternative area is secured by using free capacity of the system. 3. The control means determines the free space in the file system as a total capacity of the file system minus a used capacity and a margin capacity to be secured for future use in the file system. Disk array system described in. When a failure of a physical disk is detected, alternative area reservation request information including information that uniquely identifies the logical disk including the physical disk is created, and the replacement area of the failed physical disk is created, including the alternative area reservation request information. further comprising a second control means for requesting the control means to secure,
The control means uses information that uniquely identifies a logical disk that includes the failed physical disk, which is included in the alternative area reservation request information from the second control means, to replace a logical disk that does not include the failed physical disk. Identify,
The disk array system according to any one of claims 1 to 3. The second control means further includes information regarding the capacity of the failed physical disk in the alternative area reservation request information, and sends a request to secure an alternative area for the failed physical disk by including the alternative area reservation request information. to the control means,
The control means specifies the capacity required for the alternative area using information regarding the capacity of the physical disk included in the alternative area reservation request information from the second control means.
The disk array system according to claim 4. The control means secures the alternative area if the capacity of the physical disk included in the alternative area reservation request information cannot be secured using the free space of a file system built on a logical disk that does not include the physical disk. 6. The disk array system according to claim 5, wherein it is determined that the disk array system cannot be used . The second control means copies the contents of a non-faulty physical disk constituting a logical disk including the failed physical disk to the alternative area when the control means secures the alternative area. ,
The disk array system according to any one of claims 4 to 6. Upon securing the alternative area, the control means generates an alternative area management table for managing the alternative area;
The second control means requests the control means to write to the alternative area when writing to the failed physical disk is necessary to maintain the RAID configuration;
When the control means receives a write request to the alternative area from the second control means, the control means performs a write process to the alternative area using the alternative area management table.
The disk array system according to any one of claims 4 to 7. A system that configures RAID in a disk array, where multiple logical disks are configured using the entire capacity of multiple physical disks, and each file system is configured using the entire capacity of each logical disk. On the other hand, by computer,
When one of the plurality of physical disks fails, find free space in a file system built on a logical disk that does not include the failed physical disk,
A method for a disk array system, wherein a substitute area for a failed physical disk is secured for a file system built on a logical disk including the failed physical disk by using the free space. A system that configures RAID in a disk array, where multiple logical disks are configured using the entire capacity of multiple physical disks, and each file system is configured using the entire capacity of each logical disk. On the other hand ,
When one of the plurality of physical disks fails, find free space in a file system built on a logical disk that does not include the failed physical disk,
A computer for a disk array system that causes a computer to use the free space to secure an alternative area for a failed physical disk for a file system built on a logical disk that includes the failed physical disk. program.

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