Storage control device, storage management method, and program

Abstract

To provide a storage control device capable of reducing the number of physical drives used to construct a RAID.SOLUTION: A storage control device comprises: host control means for requesting the construction of a virtual disk and a logical drive of RAID1; disk chunk control means for registering a plurality of virtual disk chunks registered in an unused virtual disk chunk table for managing the virtual disk chunks not used for virtual disk construction among virtual disk chunks where unused storage regions of a physical drive are divided, in a virtual disk management table as a storage region for constructing a new virtual disk, and constructing a logical drive of RAID1 with the new virtual disk and other physical drives as components; and disk control means for reading and writing the storage region registered in the virtual disk management table according to a request from the disk chunk control means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a storage control device and the like. [Background technology]

[0002] 2. Description of the Related Art A redundant array of independent disks (RAID) is often constructed using a plurality of physical disk drives.

[0003] Patent Document 1 discloses a disk array device that uses unused areas of a plurality of storage devices that are redundantly configured using RAID to create a virtual alternative disk area.

[0004] Patent Document 2 discloses a disk control device that constructs a RAID using some of the partitions included in multiple storage devices as components. The disk control device of Patent Document 2 reconstructs a RAID using a partition included in a new storage device and multiple partitions that constitute the RAID or a partition that does not constitute the RAID as components. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-142632 A [Patent Document 2] JP 2016-091164 A Summary of the Invention [Problem to be solved by the invention]

[0006] In order to add storage capacity to a disk array device, a new RAID can be constructed using multiple physical disks. When constructing a new RAID, even if only a small amount of storage capacity is added, the cost of multiple physical disks is incurred.

[0007] One of the objects of the present disclosure is to provide a storage device or the like that makes it possible to reduce the number of physical drives used to construct a RAID. [Means for solving the problem]

[0008] A storage control device according to the present disclosure includes a host control means for receiving a RAID construction command from a host and requesting the construction of a new virtual disk and a RAID1 logical drive; a disk chunk control means for managing the storage area of ​​a physical drive used to construct the virtual disk using a virtual disk management table and for managing, among virtual disk chunks obtained by dividing unused storage areas of the physical drives, the virtual disk chunks that are not used to construct the virtual disk using an unused virtual disk chunk table; and a disk control means for performing reads and writes to the storage areas registered in the virtual disk management table in response to a request from the disk chunk control means, and the disk chunk control means registers, in the virtual disk management table, a plurality of the virtual disk chunks registered in the unused virtual disk chunk table in response to a request from the host control means, and constructs a RAID1 logical drive using the new virtual disk and at least one other physical drive as components.

[0009] The storage management method of the present disclosure divides unused storage space of a physical drive into virtual disk chunks, registers the virtual disk chunks that are not used to construct a virtual disk in an unused virtual disk chunk table, registers multiple virtual disk chunks registered in the unused virtual disk chunk table in a virtual disk management table as storage space for constructing a virtual disk, and constructs a RAID1 logical drive using one of the virtual disks and at least one other physical drive as components.

[0010] A program according to the present disclosure causes a computer to execute a process of dividing an unused storage area of ​​a physical drive into virtual disk chunks, registering the virtual disk chunks not used in constructing a virtual disk in an unused virtual disk chunk table, registering the virtual disk chunks registered in the unused virtual disk chunk table in a virtual disk management table as storage areas for constructing a virtual disk, and constructing a RAID1 logical drive using one of the virtual disks and at least one other physical drive as components. The program may be stored in a computer-readable non-transitory recording medium. Effect of the Invention

[0011] According to the present disclosure, it is possible to reduce the number of physical drives used to construct a RAID. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a functional block diagram illustrating a configuration example of a storage control device. [Diagram 2] 13 is a flowchart showing an example of an operation for additionally constructing a RAID. [Diagram 3] FIG. 2 illustrates an example of a usage state of a storage area of ​​a physical disk. [Figure 4] FIG. 13 is a diagram illustrating an example of a state in which an unused area is divided. [Diagram 5] 13A and 13B are diagrams illustrating an example of a virtual disk management table and an unused virtual disk chunk table in a normal state. [Figure 6] FIG. 13 is a diagram illustrating an example of a state in which RAID1 is newly constructed. [Figure 7] 13 is a flowchart showing an example of a read / write operation. [Figure 8] FIG. 13 illustrates an example of a degenerate physical disk. [Figure 9] 11A and 11B are diagrams illustrating examples of a virtual disk management table and an unused virtual disk chunk table. [Figure 10]13 is a flowchart showing an example of an operation for recovering a virtual disk. [Figure 11] FIG. 13 illustrates an example of a state in which a physical disk has been replaced with a new one having a capacity equal to or larger than that of the old physical disk. [Figure 12] FIG. 13 is a diagram illustrating an example of a table in a case where the capacity of a new physical disk is equal to or greater than the capacity of an old physical disk. [Figure 13] 13 is a diagram illustrating an example of a table used when restoring a virtual disk from an unused virtual disk chunk of a replaced physical disk. FIG. [Figure 14] FIG. 2 illustrates an example of a state in which an old physical disk is replaced with a physical disk of smaller capacity. [Figure 15] FIG. 13 is a diagram illustrating an example of a table when the capacity of a new physical disk is smaller than that of the old physical disk. [Figure 16] FIG. 13 is a diagram showing an example of a table when a virtual disk is allocated from an unused virtual disk chunk table; [Figure 17] FIG. 13 is a diagram illustrating an example of a state in which RAID is restored. [Figure 18] FIG. 2 is a block diagram illustrating an example of a hardware configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] FIG. 1 is a configuration diagram showing an example of a storage control device 201 according to an embodiment.

[0014] The storage control device 201 is connected to a drive group 14 that is configured from a plurality of physical drives. The storage control device 201 and the drive group 14 may be configured as an integrated device. A device including the storage control device 201 and the drive group 14 is also called a storage device. Below, a case will be described in which the drive group 14 is configured from a plurality of physical disks 15 such as HDDs (hard disk drives). However, the physical drives that configure the drive group 14 are not limited to this, and various types of physical drives such as SSDs (solid state drives) may be used.

[0015] The storage control device 201 is connected to the host 200 via a network. The storage control device 201 may be configured as an integrated device with the host 200. The host 200 issues a RAID construction command and an I / O (Input / Output) command to the storage control device 201.

[0016] The storage control device 201 includes a host control unit 10 , a virtual disk management table 11 , an unused virtual disk chunk table 12 , a disk control unit 13 , and a disk chunk control unit 16 .

[0017] The host control unit 10 receives a RAID construction command and an I / O command from the host 200. Then, the host control unit 10 makes a RAID construction request or a read / write request to the disk chunk control unit 16 in accordance with the command, and returns the result to the host 200.

[0018] When the host control unit 10 receives the RAID construction command, it sends a construction request for a virtual disk to the disk chunk control unit 16. In the following description, a virtual disk is a disk in which unused areas of multiple physical disks are integrated and treated as if they were a single physical disk. The unused areas of each physical disk are divided into virtual disk chunks of a certain unit, for example.

[0019] The virtual disk management table 11 is a table for managing unused areas of physical disks used by virtual disks. The virtual disk management table 11 includes data such as virtual disk numbers, virtual disk capacities, and virtual disk chunk numbers used by the virtual disks.

[0020] The unused virtual disk chunk table 12 is a table for managing unused areas that are not used in constructing a virtual disk. The unused virtual disk chunk table 12 includes, for example, data on virtual disk chunk numbers that are not used in a virtual disk.

[0021] The disk chunk control unit 16 creates a virtual disk management table 11 and an unused virtual disk chunk table 12 and registers information in each table in response to a request from the host control unit 10. The disk chunk control unit 16 also requests the disk control unit 13 to perform read / write operations.

[0022] For example, the disk chunk control unit 16 divides an unused area of ​​a physical disk into certain units. The disk chunk control unit 16 may also assign a virtual disk chunk number to each virtual disk chunk. For example, the disk chunk control unit 16 registers the virtual disk number, the capacity of the virtual disk, and the virtual disk chunk number in the virtual disk management table 11 to construct a virtual disk.

[0023] The disk control unit 13 constructs a RAID or performs read / write on the physical disk 15 in response to a request from the disk chunk control unit 16 .

[0024] In Fig. 1, the drive group 14 is composed of a plurality of physical disks 15. As an example, the physical disks 15 are used to construct a logical drive having a RAID configuration. In Fig. 1, RAIDs 100 and 101 have a RAID configuration. The number of logical drives having a RAID configuration to be constructed is not particularly limited. Furthermore, the type of RAID to be constructed and the number of physical disks 15 to be used to construct the RAID are not particularly limited.

[0025] An example of a method for additionally constructing a RAID1 according to an embodiment will be described with reference to Fig. 2. Fig. 2 is a flowchart showing an example of the operation of the storage control device 201 when additionally constructing a RAID. In one embodiment, the host 200 may transmit an additional construction command for RAID1 when a RAID has already been constructed in the drive group 14. The following describes an example in which the RAID100 in Fig. 1 has already been constructed as RAID5, and the RAID101 has already been constructed as RAID1.

[0026] 3 is a diagram showing an example of the usage state of storage areas of physical disks constituting the RAIDs 100 and 101. Physical disks 1-0, . . . , and 1-7 each correspond to the physical disk 15 in FIG.

[0027] 2 in response to, for example, receiving a RAID construction command from the host 200. The host control unit 10 requests the disk chunk control unit 16 to construct a virtual disk (step S101).

[0028] In response to a request from the host control unit 10, the disk chunk control unit 16 determines whether the physical disks have unused areas (step S102). For example, the disk chunk control unit 16 determines whether the physical disks 1-0, . . . , 1-7 in FIG. 3 have unused areas.

[0029] If there is unused space (step S102: YES), the unused space is divided at a fixed ratio (step S103). Fig. 4 is a diagram showing an example of a state in which the unused space is divided. For example, the disk chunk control unit 16 divides the unused space into virtual disk chunks 3-0, ..., 3-5 as shown in Fig. 4. In addition, the disk chunk control unit 16 assigns virtual disk chunk numbers (0xa00, ..., 0xf00).

[0030] Next, the disk chunk control unit 16 determines the capacity of the virtual disk to be used for the additionally constructed RAID1 (step S104). For example, the disk chunk control unit 16 determines the capacity of the virtual disk to be the same as the capacity of the physical disk to be used for the additionally constructed RAID1. The capacity of the virtual disk is the total capacity of the virtual disk chunks to be used.

[0031] The disk chunk control unit 16 determines whether the total capacity of all the virtual disk chunks is equal to or greater than the capacity of the determined virtual disk (step S105). For example, the disk chunk control unit 16 refers to the unused virtual disk chunk table 12 to determine whether the total capacity of all the virtual disk chunks is equal to or greater than the capacity of the determined virtual disk.

[0032] If the total capacity is equal to or greater than the capacity of the virtual disk (step S105: Yes), the disk chunk control unit 16 determines a virtual disk chunk to be used for the virtual disk. Then, the disk chunk control unit 16 registers the virtual disk chunk in the virtual disk management table 11 and the unused virtual disk chunk table 12 (step S106). FIG. 5 is a diagram showing an example of the virtual disk management table 11 and the unused virtual disk chunk table 12.

[0033] The capacity of the virtual disk can be increased by increasing the number of virtual disk chunks, so the storage control device 201 can configure virtual disks of various capacities.

[0034] Next, the disk control unit 13 constructs RAID1 with the virtual disk constructed by the disk chunk control unit 16 and the new physical disk (step S108). Fig. 6 is a diagram showing the state in which RAID1 has been newly constructed. In Fig. 6, RAID1 is constructed with the virtual disk 11-0 and the newly added physical disk 1-8. The same data is duplicated and recorded on the virtual disk 11-0 and the physical disk 1-8.

[0035] There are cases where there is no unused space in the physical disks constituting the constructed RAID (step S102: No), and cases where the total capacity of all disk chunks is less than the capacity of the determined virtual disk (step S105: No). In these cases, the disk control unit 13 constructs RAID1 using only the physical disks (step S107).

[0036] The disk chunk control unit 16 returns the result of the RAID construction to the host control unit 10 (step S109). With the above, the storage control device 201 ends the operation of Fig. 2. Note that if the total capacity of all the disk chunks is less than the capacity of the determined virtual disk (step S105: No), the disk chunk control unit 16 may determine the total capacity of all the disk chunks as the capacity of the virtual disk. Thereafter, the disk chunk control unit 16 may execute step S106 and subsequent steps.

[0037] Next, an example of read / write of a RAID constructed using a virtual disk will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the operation of the storage control device 201 in read / write. The storage control device 201 may start the process of Fig. 7 in response to the host control unit 10 receiving a read / write request from the host 200.

[0038] The disk chunk control unit 16 refers to the virtual disk management table 11 and identifies a virtual disk chunk corresponding to the address (LD / LBA, Logical Disk / Logical Block Address) to be read / written (step S111). Then, the disk chunk control unit 16 transmits a read / write request for the identified address to the disk control unit 13 (step S112). The disk control unit 13 performs read / write by accessing the requested address (step S113). The disk control unit 13 returns the execution result of the read / write to the host control unit 10 (step S114).

[0039] With the above, the storage control device 201 ends the operation of Fig. 7. After step S114, the host control unit 10 returns the execution result of the read / write to the host 200.

[0040] Next, an example of a method for restoring a virtual disk when a physical disk is degenerated will be described. FIG. 8 is a diagram showing a state in which the physical disk 1-0 in FIG. 6 is degenerated. When the physical disk 1-0 to which a virtual disk chunk belongs is degenerated, the virtual disk chunk becomes unusable. Therefore, the virtual disk 11-0 is in a degenerated state. The disk chunk control unit 16 identifies the degenerated virtual disk chunk, and registers in the virtual disk management table 11 that the virtual disk chunk is invalid. FIG. 9 is a diagram showing an example of the virtual disk management table 11 and the unused virtual disk chunk table 12 when the physical disk 1-0 is degenerated.

[0041] The operation of the storage control device 201 when restoring a virtual disk will be described with reference to the flowchart of Fig. 10. For example, the storage control device 201 starts the process of Fig. 10 when a degenerated physical disk is replaced with a new physical disk.

[0042] Fig. 11 shows an example of a state in which the physical disk 1-0 in Fig. 6 has been replaced with a physical disk 1-0'. In Fig. 11, the capacity of the replaced physical disk is equal to or greater than the capacity of the old physical disk.

[0043] The disk chunk control unit 16 updates the information in the virtual disk management table 11 and the unused virtual disk chunk table 12 (step S201). FIG. 12 is a diagram showing an example of the updated virtual disk management table 11 and the unused virtual disk chunk table 12. The tables in FIG. 9 are updated to the table in FIG. 12 when the state of FIG. 11 is reached. For example, the disk chunk control unit 16 deletes invalid virtual disk chunks from the virtual disk management table 11 and the unused virtual disk chunk table 12. The disk chunk control unit 16 also divides the unused area of ​​the new physical disk 1-0'. Then, the disk chunk control unit 16 assigns disk chunk numbers to the virtual disk chunks 3-0', 3-1', and 3-6' and registers them in the unused virtual disk chunk table 12.

[0044] If the virtual disk management table 11 contains an area of ​​the degenerated physical disk (step S202: Yes), the disk chunk control unit 16 judges whether the new replaced physical disk has a sufficient unused area for configuring a virtual disk. In the example of Fig. 10, for example, the disk chunk control unit 16 compares the capacities of the new replaced physical disk and the old physical disk (step S203). Note that, for the judgment, the disk chunk control unit 16 may compare the unused area of ​​the new physical disk with the unused area of ​​the old physical disk.

[0045] If the capacity of the replaced physical disk is equal to or larger than the capacity of the old physical disk (step S203: Yes), the disk chunk control unit 16 registers unused virtual disk chunks in the virtual disk management table 11. The number of virtual disk chunks to be registered is determined from the difference between the virtual disk capacity already registered in the virtual disk management table 11 and the capacity of the registered virtual disk chunks. FIG. 13 is a diagram showing an example of the updated virtual disk management table 11 and the unused virtual disk chunk table 12. The table in FIG. 12 is updated to the table in FIG. 13 when the unused virtual disk chunks 3-0', 3-1' in FIG. 11 are registered.

[0046] Then, the disk chunk control unit 16 restores the data to the updated virtual disk management table 11 (step S204). For example, the disk chunk control unit 16 instructs the disk control unit 13 to write data from the normal physical disk 1-8 to the registered virtual disk chunks 3-0' and 3-1'. In this way, the disk chunk control unit 16 can preferentially allocate the unused area of ​​the new physical drive to the restoration of the virtual disk.

[0047] There may be cases where the capacity of the replaced physical disk is smaller than the capacity of the old physical disk (step S203: No). In such a case, the replaced new physical disk will lack unused space. If the new physical disk does not have enough unused space, the disk chunk control unit 16 determines whether there are sufficient virtual disk chunks that can be added to the virtual disk management table 11 to configure the virtual disk (step S205). Whether a virtual disk chunk can be added can be determined from the state in which the virtual disk chunks are registered in the unused virtual disk chunk table 12. Whether there are sufficient virtual disk chunks may be determined based on whether there is a sufficient number of virtual disk chunks.

[0048] Fig. 14 shows another example of a state in which the physical disk 1-0 in Fig. 6 has been replaced with a physical disk 1-0'. In Fig. 14, the capacity of the replaced physical disk is smaller than the capacity of the old physical disk.

[0049] In step S201, in the state of Fig. 14, virtual disk management table 11 and unused virtual disk chunk table 12 are updated as shown in Fig. 15. Virtual disk chunks 3-0 and 3-1 that were used in the virtual disk before the degeneration become unusable. That is, the area of ​​the degenerated physical disk exists in virtual disk management table 11. Only virtual disk chunks 3-2 and 3-3 that were registered before the disk replacement are registered in virtual disk management table 11. Also, virtual disk chunks 3-4 and 3-5 exist in unused virtual disk chunk table 12.

[0050] If a virtual disk chunk exists in the unused virtual disk chunk table 12 (step S205: Yes), the disk chunk control unit 16 adds the virtual disk chunk in the unused virtual disk chunk table 12 to the virtual disk management table 11 (step S206). The number of virtual disk chunks to be added is determined from the difference between the capacity of the virtual disk chunk registered in the virtual disk management table 11 and the capacity of the registered virtual disk.

[0051] 14, in place of the virtual disk chunks 3-0 and 3-1 which have become unavailable, the disk chunk control unit 16 adds virtual disk chunks 3-4 and 3-5 which are in a normal state. FIG 16 is a diagram showing the updated virtual disk management table 11 and the unused virtual disk chunk table 12.

[0052] The disk chunk control unit 16 restores the data to the area thus added (step S207). For example, the disk chunk control unit 16 instructs the disk control unit 13 to write data from the normal physical disk 1-8 to the added virtual disk chunks 3-4 and 3-5. Fig. 17 is a diagram showing the state in which the RAID has been restored.

[0053] If there are not enough virtual disk chunks in the unused virtual disk chunk table 12 (step S205: No), the disk chunk control unit 16 suspends the construction of the virtual disk and waits for a physical disk to be added (step S208). In step S208, the disk chunk control unit 16 may output an instruction to add a physical disk. When a physical disk is added, the disk chunk control unit 16 restores data from a physical disk in a normal state to the added physical disk (step S209).

[0054] With the above, the storage device completes the operation of FIG.

[0055] Here, the cancellation of a virtual disk will be explained. The disk chunk control unit 16 cancels the RAID constructed by the virtual disk and the physical disk. The disk chunk control unit 16 cancels the virtual disk together with canceling the RAID. For example, the disk chunk control unit 16 deletes the virtual disk chunk and the virtual disk capacity registered in the virtual disk management table 11. The disk chunk control unit 16 registers the virtual disk chunk deleted from the virtual disk management table 11 in the unused virtual disk chunk table 12.

[0056] According to one embodiment, the disk chunk control unit 16 constructs a virtual disk using unused storage areas of physical disks. The disk chunk control unit 16 then constructs RAID1 using one virtual disk and one physical disk as components. This makes it possible to reduce the number of physical disks to be added to a new RAID construction.

[0057] According to one embodiment, the unused virtual disk chunk table 12 manages information on unused storage areas of physical disks. Therefore, it is possible to collectively manage virtual disks. Therefore, when constructing a virtual disk or restoring a virtual disk, it is possible to efficiently specify unused areas, determine areas required for each operation, and register them.

[0058] Furthermore, according to one embodiment, the virtual disk management table 11 manages the virtual disk chunks used to construct the virtual disk. This makes it easy to identify the address for reading and writing data. This makes it possible to speed up reading and writing data from and to the virtual disk.

[0059] [Hardware configuration] In the above-described embodiment, each component of the storage control device 201 is represented by a functional block. A part or all of each component of the storage control device 201 may be realized by any combination of a computer 500 and a program.

[0060] Fig. 18 is a block diagram showing an example of a hardware configuration of a computer 500. Referring to Fig. 18, the computer 500 includes, for example, a processor 501, a read only memory (ROM) 502, a random access memory (RAM) 503, a program 504, a storage device 505, a drive device 507, a communication interface 508, an input device 509, an input / output interface 511, and a bus 512.

[0061] The processor 501 controls the entire computer 500. An example of the processor 501 is a CPU (Central Processing Unit). The number of processors 501 is not particularly limited, and the processor 501 may be one or more.

[0062] The program 504 includes instructions for implementing each function of the storage control device 201. The program 504 is stored in advance in the ROM 502, the RAM 503, or the storage device 505. The processor 501 implements each function of the storage control device 201 by executing the instructions included in the program 504. The RAM 503 may also store data to be processed in each function of the storage control device 201.

[0063] The drive device 507 reads and writes data from and to the recording medium 506. The communication interface 508 provides an interface with a communication network. The input device 509 is, for example, a mouse or a keyboard, and receives information input from an administrator or the like. The output device 510 is, for example, a display, and outputs (displays) information to an administrator or the like. The input / output interface 511 provides an interface with peripheral devices. The bus 512 connects these hardware components. The program 504 may be supplied to the processor 501 via a communication network, or may be stored in advance in the recording medium 506, read out by the drive device 507, and supplied to the processor 501.

[0064] It should be noted that the hardware configuration shown in FIG. 18 is merely an example, and other components may be added, or some components may not be included.

[0065] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, the configurations in each embodiment can be combined with each other without departing from the scope of the present disclosure. [Explanation of symbols]

[0066] 200 Host 201 Storage control device 10 Host control section 11 Virtual Disk Management Table 12 Unused Virtual Disk Chunk Table 13 Disk control section 14 Drives 15, 1-0, ..., 1-8 Physical Disks 16 Disk chunk control section 100, 101 RAID 300, 301 unused area 11-0 Virtual Disk 3-0, ..., 3-6 Virtual Disk Chunks

Claims

1. a host control means for receiving a RAID construction command from a host and requesting construction of a new virtual disk and a RAID 1 logical drive; a disk chunk control means for managing a storage area of ​​a physical drive used to construct a virtual disk by using a virtual disk management table, and for managing virtual disk chunks obtained by dividing unused storage areas of the physical drive, which are not used to construct the virtual disk, by using an unused virtual disk chunk table; a disk control means for performing read / write to the storage area registered in the virtual disk management table in response to a request from the disk chunk control means; Equipped with The disk chunk control means registering the plurality of virtual disk chunks registered in the unused virtual disk chunk table in the virtual disk management table as storage areas for constructing the new virtual disk in response to a request from the host control means; A RAID 1 logical drive is constructed using the new virtual disk and at least one other physical drive as components. Storage control device.

2. The unused storage area is a storage area of ​​a physical drive that constitutes a logical drive of a RAID that is not used to construct the logical drive of the RAID. The storage control device according to claim 1 .

3. The disk chunk control means allocates, to the recovery of the virtual disk, an unused storage area of ​​a new physical drive that has been replaced with the physical drive used to construct the virtual disk, with priority. The storage control device according to claim 1 .

4. When the unused storage area is insufficient for restoring the virtual disk after the physical drive used to construct the virtual disk is replaced with a new physical drive, the disk chunk control means interrupts the restoration of the virtual disk and restores the RAID 1 logical drive using another new physical drive. The storage control device according to claim 1 .

5. The disk chunk control means outputs an instruction to add another new physical disk when the unused storage area is insufficient for restoring the virtual disk. The storage control device according to claim 4.

6. Divide unused storage space on physical drives into virtual disk chunks registering the virtual disk chunks that are not used to construct a virtual disk in an unused virtual disk chunk table; registering the plurality of virtual disk chunks registered in the unused virtual disk chunk table in a virtual disk management table as storage areas for constructing a virtual disk; A RAID 1 logical drive is constructed using one of the virtual disks and at least one other physical drive as components. Storage management methods.

7. Divide unused storage space on physical drives into virtual disk chunks registering the virtual disk chunks that are not used to construct a virtual disk in an unused virtual disk chunk table; registering the plurality of virtual disk chunks registered in the unused virtual disk chunk table in a virtual disk management table as storage areas for constructing a virtual disk; A RAID 1 logical drive is constructed using one of the virtual disks and at least one other physical drive as components. A program that causes a computer to carry out processing.

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