JP3172872B2 - Storage device and data restoration method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device for reading and writing data in parallel by using a plurality of independent storage media as a set, and a data correction method for the storage device.

[0002]

2. Description of the Related Art As a conventional technique, as a technique for increasing the capacity of a storage device and transferring data at a high speed, data is divided into bit units, byte units, or arbitrary units by using a plurality of storage media as a set. There is known a method in which each data is distributed and stored in each storage medium, and data is simultaneously read from each storage medium when data is read. In this method, data for parity check is generated from the data distributed to each storage medium, and this is stored in another storage medium. When a failure occurs, the data is restored using the data of the normal storage medium and the data for parity check, thereby improving the reliability of the storage device. Examples of these techniques are described in JP-A-1-250128. Further, there is known a technique in which when a failure occurs in a storage medium, not only data is restored for normal reading, but also data of the failed medium is restored to a separately prepared normal storage medium. This technique can increase the availability of a storage device by storing restored data in a spare medium and reading data from the spare medium for the next access. For example, Japanese Patent Laid-Open No. 2-1
Japanese Patent No. 35555 discloses an example of this type of storage device.

[0003]

The above-mentioned known apparatus can repair a failure of a fixed number of storage media by having parity data, and can also perform failure recovery by having a spare storage medium. I can do it. However, the failure recovery operation requires an operation of reading out all data of a normal storage medium and data for parity check, repairing the failure data, and writing the data to a spare storage medium. Therefore, during the recovery from a failure, each storage medium is occupied, and even if a normal read / write processing request is received from a higher-level device, it is waited for, and as a result, the performance of the storage device is reduced. Also,
The above-mentioned known apparatus handles the failure recovery of one storage medium and the failure recovery of a plurality of failures without distinction even though there is redundancy with respect to the failure of a plurality of storage media. For this reason, if emphasis is placed on failure recovery, normal read / write processing cannot be performed despite the occurrence of one failure, and there is a problem that normal read / write processing is reduced. On the other hand, normal read / write processing is emphasized. When there are a plurality of faults, a fault recovery time is not guaranteed in the case of a plurality of faults, and there is a problem that the possibility that the entire device will break down increases. The present invention relates to a storage device having redundancy with respect to a failure of two or more storage media, minimizing a decrease in normal read / write processing at the time of failure, keeping failure recovery time within a certain time, and achieving high reliability. Is to ensure the quality.

[0004]

An object of the present invention is to provide a storage medium group that stores a plurality of independent storage media as a set and divides data into bits, bytes, or arbitrary units, and stores the divided data in the divided data. A disk for storing the corresponding ECC data, a spare storage medium for storing the restored data,
An input / output-fault recovery control circuit that receives and executes instructions related to input / output from a higher-level device and executes or responds to the higher-level device; a timer for knowing a fault occurrence time, an elapsed time during fault recovery, a unit time, and the like; A failure recovery table for a storage medium, and a failure data recovery / recovery circuit for finding, repairing, and writing to a spare storage disk the failure data, and when a failure occurs in the storage medium, the failure data recovery / recovery circuit The fault is found by error check, and the fault is notified to the input / output-fault recovery control circuit.
A failure recovery control circuit determines the state of the failure, selects and executes the priority of normal read / write or failure recovery processing suitable for the failure state, or executes the normal read / write and failure recovery processing frequency or processing ratio. Is achieved by setting

[0005]

When a failure occurs in the storage device, the redundancy of the storage device, the elapsed time of failure recovery, the state of normal read / write processing, and the like are determined, and a failure recovery process (method) suitable for the determination is selected. It is possible to prevent a decrease in the processing performance of normal reading and writing, and to ensure high reliability of the storage device. That is, when the number of failed storage media has a margin for the redundancy of the storage device, a normal read / write process is prioritized, and a failure recovery process (method) for performing a failure recovery in the remaining time is selected. Therefore, when no load is imposed on the normal read / write processing, and when there is no more margin in the redundancy, priority is given to the failure recovery processing, so that the reliability against the failure of the storage device can be ensured. Further, when there is a margin in the redundancy, the failure recovery processing (method) is changed depending on the total amount of time used for the failure recovery for the storage medium being recovered from the failure, so that the normal read / write processing is performed. Prevent performance degradation,
Failure recovery time can be set within a fixed time. Further, it is possible to select a normal time period during which normal reading and writing are less, for example, at night, and concentrate on the recovery from the failure, thereby reducing the load on the storage device during a normal reading and writing time period. Further, since the frequency of the failure recovery processing or the ratio of the amount of failure recovery is set in accordance with the magnitude of the normal read / write processing frequency, the failure recovery processing can be executed efficiently in terms of time.

[0006]

Embodiments of the present invention will be described below in detail. In the embodiment, a magnetic disk will be described as an example of a storage medium. FIG. 1 is a flowchart showing the procedure of a failure recovery process according to the present invention. FIG. 2 is a configuration diagram of an embodiment in which the present invention is applied to a storage device that can withstand two data disk failures. FIG. 3 is a failure recovery table for the failed disk in FIG. FIG. 4 is a flowchart showing a procedure of a failure recovery process in the storage device of FIG. FIGS. 5, 6, 7, 8 and 9 are diagrams showing details of the failure recovery processing selection block in the processing procedure of FIG.

[0007] A flowchart showing the processing procedure of the failure recovery of FIG. 1 will be described. It is assumed that a failure has occurred in the storage device (step 10). First, it is determined whether the fault that has occurred can be recovered (step 20). If the data cannot be repaired, the failure recovery process is terminated and data loss occurs (step 30). If repair is possible, it is determined whether the storage device is in a state in which it is necessary to concentrate on the recovery from the redundancy of the storage device, the elapsed time of the recovery from the failure, and the processing state of the normal read / write processing (step 40). If you have enough time,
When the urgency of failure recovery is low and a normal processing request such as read / write is received from the host device, the failure recovery processing is stopped and normal processing such as read / write is performed first. The failure recovery processing is performed in the remaining time, and the read / write processing during the failure recovery processing is canceled or queued (step 50). Conversely, if there is no room and the urgency of failure recovery is high, priority is given to failure recovery processing, and all normal processing such as reading and writing is canceled or queued (step 60). Also, if there is some combination between the urgency of disaster recovery and the importance of normal processing such as reading and writing, disaster recovery processing corresponding to each condition is prepared in advance in the form of a program, and the conditions change. If so, the program can be switched to an appropriate process by replacing the program (step 70). Next, when the failure recovery processing ends or is interrupted, it is checked whether or not the failure recovery processing still remains (step 80). When all the failure recovery is completed, the storage device returns to the normal state. If the fault recovery process still remains, the process returns to the beginning (20), and the above steps are repeated until the fault recovery ends.

Next, the configuration of the embodiment of the present invention shown in FIG. 2 will be described. In FIG. 2, reference numeral 150 denotes an input / output-fault recovery control circuit which receives an input / output command from a higher-level device, executes the command, or responds to the higher-level device. Further, when a failure has occurred in the storage medium, an appropriate failure recovery method is selected from the number of disks during the recovery, the time required for the recovery, the frequency of the recovery or the amount of the recovery. Reference numeral 154 denotes a failure recovery table of the failure storage medium, which will be described in detail with reference to FIG. Reference numeral 152 denotes a timer for knowing the fault occurrence time, the elapsed time during the fault recovery, and the unit time, and determines the fault recovery method using the time measured here as one condition. Reference numeral 156 denotes a failure data recovery / recovery circuit for finding, restoring, and writing to the spare storage disk. The failure data recovery / recovery circuit reads data from all disks except the failed disk, and uses the read data to repair the failed data. The data is transferred to the device or written to a spare storage disk. Data disk groups 158 to 168 store divided data. FIG.
In the above, six disks are shown as the number of data disks, but the number is generally arbitrary. 170 and 172 are 158
This is a disk for storing ECC data corresponding to data divided into 168 and 168. When a fault occurs, the fault data is restored using this data and the normal data in 158 to 168. However, if more data disks fail than the redundancy of the storage device, the data cannot be repaired, resulting in data loss. In FIG. 2, the ECC data is 2
In other words, even if two data disks have failed, the failed data can be repaired. However, in general, an EC that can withstand two or more disk failures
There is also a C generation method, and the number of failed disks that do not lead to data loss, that is, the redundancy can be further increased.
Specifically, the ECC generation method is realized by using a Reed-Solomon code capable of multiple erasure correction. The Reed-Solomon code and the error correction method using the same are described in the related art (for example, described in "New Edition Digital Audio" published by Doi and Iga, published by Radio Engineering Co., Ltd.), and thus description thereof is omitted. . Reference numerals 174 and 176 denote spare storage media for storing the restored data. When the contents of the failed disk are stored, access to the data from the next time becomes the spare storage media. This number of disks is also generally arbitrary.

The failure recovery table for the failed disk shown in FIG. 3 will be described. The failure recovery table 154 determines the identification number (1) of the spare storage disk, the identification number (2) of the failed disk, the failure time (3), the address of the failed data (4), and the presence or absence of the failure recovery. It consists of a flag (5).

Next, based on the flowchart of FIG.
And the operation of FIG. First, assume that a failure has occurred in the data disk 162 in FIG. 2 (100). The fault data recovery / recovery circuit 156 detects the fault, and
The occurrence of a fault is notified to the fault recovery control circuit 150. The input / output-fault recovery control circuit 150, which has been notified from the fault data recovery / recovery circuit 156, checks the fault recovery table 154 to determine whether there is a free space (102). Next, the input / output-fault recovery control circuit 150 confirms that this fault is a new fault (104). If it is a new fault, I / O-
The fault recovery control circuit 150 is used for the fault data recovery and recovery circuit 15.
6 instructs to write an initial value in a corresponding column in the failure recovery table 154. The failure data recovery / recovery circuit 156 writes the identification number S1 of the spare disk 174 in the column of the spare storage medium in the failure recovery table 154, and the identification number # 2 of the failed data disk 162 in the column of the failure storage medium. Write. Next, timer 15
2 is written in the column of failure time, and the address of the failed disk 162 is written in the address column. Finally, the failure data recovery / recovery circuit 156 initializes a recovery determination flag of each address (106). If it is not a new fault, the process proceeds to the next step without performing the process of step 106. In the next step, the input / output-fault recovery control circuit 150 determines the status of the fault, selects and executes a normal read / write process or a fault recovery process suitable for the fault (108). Details of this step will be described with reference to FIGS. Next, when the failure recovery processing ends or is interrupted, it is checked whether the failure recovery processing still remains (11).
0). When all of the failure recovery is completed, the storage device returns to the normal state. If the failure recovery process still remains, the process returns to the beginning (102), and the above steps are repeated until the failure recovery is completed. Regardless of the failure recovery method, the failure data recovery / recovery circuit 156 monitors the continuation or termination of the failure recovery. If the next failure occurs before the failure recovery is completed, the failure data recovery / recovery circuit 156 starts processing as described above (102).
If the number of failed disks for which the failure recovery is not completed exceeds the redundancy of the device, recovery from the failure is impossible, so the I / O-fault recovery control circuit 150 reports the data loss to the higher-level device (114). If disaster recovery is over,
Erase unnecessary data in the failure recovery table 154,
It returns to a normal state (112).

Next, step 108 in FIG. 4 will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 5, the input / output-failure recovery control circuit 150 looks at the failure recovery table 154, counts the number of disks for which recovery has not been completed, and compares the number of failure disks with a threshold (step 120). If the number of failed disks is less than a predetermined threshold, the I / O-failure recovery control circuit 150 determines that there is enough redundancy, gives priority to normal reading and writing, and performs the failure recovery process at other times. Do. Those in the middle of the failure recovery processing are canceled or queued (step 122). If the number of failed disks is larger than the threshold value, the I / O-failure recovery control circuit 150 determines that there is no margin in the redundancy, gives priority to the failure recovery processing, and cancels or queues all normal processing such as reading and writing. (Step 12
4). When recovering from a failure, the recovery and storage are completed in a relatively short time, such as one track, and the storage device is released for normal processing after the completion. However, if a normal read / write processing instruction is received during recovery from a failure, the failure recovery work is immediately stopped and released for normal read / write processing. When reading data for which failure recovery has not been completed during normal read / write processing, the failed data is repaired with the ECC data and the normal data used to generate it, sent to the upper-level device, and simultaneously stored in the spare disk. In the recovery table 154, the recovery determination flag of the corresponding address in the recovery table 154 is determined to have been recovered. If this flag indicates that the recovery has been completed, the next access to this data will be made to the spare disk. In the case of data writing, after the ECC data is created, data to be stored in the failed disk is written to the spare disk, and the recovery determination flag is set to "recovered". The threshold value is necessarily 1 since the redundancy is two in the example of FIG. However, when two or more multiplex erasure-correctable Reed-Solomon codes are used, the threshold can take any integer less than or equal to the redundancy. The fault recovery stores the address of the data previously recovered by the input / output-fault recovery control circuit 150, and starts from the next address. At the time of failure recovery, the previously stored data address stored previously is used. If the next address is not flagged in the failure recovery table 154 and the failure recovery is not completed, the data at that address is repaired. . To restore the data, the normal data used to generate the ECC data from the ECC data and the normal disk is read, and the faulty data recovery and recovery circuit 156 is used.
Perform using. The repaired data is written to a spare disk, and the flag in the failure recovery table 154 is set to "recovered". Access to the data that has been restored will be made to the spare disk. The address of the restored data is stored in the failure data restoration and recovery circuit 156, and the input / output
The fault recovery control circuit 150 proceeds to the next fault recovery process. In the embodiment shown in FIG. 5, when the number of failed disks is equal to or smaller than the threshold value, the normal read / write processing is prioritized over the recovery from the failure. In addition, in a state where the user concentrates on the recovery from the failure, the repair can be performed in the shortest time, so that the reliability can be maintained. In the above embodiment, the failure recovery method is selected by paying attention only to the number of failed disks, but the condition may also include the total failure recovery time in addition to the number of failed disks.

Next, step 108 in FIG. 4 will be described with reference to FIG. In FIG. 6, the input / output-failure recovery control circuit 150 looks at the failure recovery table 154, counts the number of disks for which recovery has not been completed, and compares the number of failed disks with a threshold value (step 130). If it is below the threshold, then the input / output-fault recovery control circuit 15
In the case of 0, the current time is read from the timer 152, and the total of the fault recovery time calculated from the current time and the fault occurrence time in the fault recovery table 154 is compared with a preset time limit (step 132). Therefore, when the total of the fault recovery times is smaller than the preset time limit, it can be considered that there is a margin for the fault recovery, so that the input / output-fault recovery control circuit 150 It gives priority to normal read / write processing, and instructs the data in the failed disk to be repaired in the remaining time and stored in the spare disk. Those in the middle of the failure recovery processing are canceled or queued (step 134). If the number of disks for which recovery has not been completed is greater than the threshold value, or if the difference between the current time and the failure time is greater than a preset time limit, it can be considered that there is no margin for recovery from failure. , The failure recovery control circuit 150
Normal reading and writing from the higher-level device is canceled or queued.
An instruction is given to perform the recovery from the failure first (step 13
6). In the embodiment shown in FIG. 6, when the time required for the recovery from the fault exceeds the time limit, the user can concentrate on the recovery from the fault, so that the repair time can be set within a fixed time, and the reliability can be improved.

Next, step 108 in FIG. 4 will be described with reference to FIG.
This will be described with reference to FIG. 7, the input / output-failure recovery control device 150 acquires the current time from the timer 152,
It is determined whether or not the time is a time zone in which normal read / write processing is frequently performed (step 140). If not, the input / output / fault recovery control circuit 150 cancels or queues the normal read / write from the host device, and gives priority to the fault data recovery / recovery circuit 156 for fault recovery. Command. If the number of failed disks in step 142 exceeds the threshold value even during that time, priority is given to the failure recovery processing in the same manner (step 14).
6). Only when normal read / write processing is large and the number of failed disks is below the threshold, normal read / write is given priority,
Failure recovery is performed in the remaining time (step 144). In the embodiment of FIG. 7, when it is known in advance that the use of the storage device differs depending on the time zone, the failure recovery can be applied to the time zone where the normal read / write processing is small. The failure recovery can be executed smoothly without the read / write processing of the data interfering with the failure recovery processing. In the above-described embodiments of FIGS. 5 to 7, two types of failure recovery processing are performed, giving priority to failure recovery or giving priority to normal reading and writing. However, the number of failure recovery processes may be increased according to the situation.

Next, step 108 in FIG. 4 will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 8, when the number of failed disks in step 150 exceeds the threshold value, priority is given to recovery from failure, and normal reading and writing are stopped (step 158). If the number of failed disks is equal to or less than the threshold value and the time period for normal read / write processing in step 152 is not a time zone, only read processing is performed, and the rest of the time is given priority to failure recovery (step 156). If the number of failed disks is equal to or less than the threshold value and there is a lot of normal read / write processing, priority is given to normal read / write processing, and failure recovery is performed at other times (step 154). In the embodiment of FIG. 8, the number of failed disks is equal to or smaller than the threshold value. However, in a time zone where normal read / write processing is small, particularly in a time zone where only reading is performed,
By exceptionally permitting the reading process, it is possible to prevent the failure recovery process and suppress the performance degradation of the storage device.

Next, step 108 in FIG. 4 will be described with reference to FIG. In FIG. 9, when the number of failed disks exceeds the threshold value in step 160, or when the number of failed disks is less than the threshold value and the total failure recovery time in step 162 exceeds the time limit, priority is given to failure recovery. Then, normal reading / writing is stopped (step 172).
The input / output-failure recovery control circuit 150 reads the unit time from the timer 152 when the number of failed disks is equal to or less than the threshold value and the total of the failure recovery times is less than the time limit, and performs a normal read / write processing frequency within the time. Is compared with a preset threshold value (step 164). If the frequency of normal reading and writing is greater than the threshold, it is within the time limit,
Since it can be considered that there is room for failure recovery, normal read / write processing is prioritized, and failure recovery is performed at other times (step 166). On the other hand, when the normal read / write processing frequency is smaller than the threshold value and the frequency is infinitely close to or far from the threshold value, there is a difference in the frequency. The frequency of the failure recovery processing per unit time or the ratio of the amount of failure recovery is dynamically set according to the magnitude of the frequency (step 168).
The failure recovery processing is executed according to the set frequency of failure recovery processing or the ratio of the amount of failure recovery (step 17).
0). In the embodiment of FIG. 9, the frequency of the failure recovery processing or the ratio of the amount of failure recovery is set in accordance with the magnitude of the normal read / write processing frequency, so that the failure recovery processing is executed efficiently in terms of time. .

In the above embodiments, a magnetic disk is taken as an example of a storage medium, but an optical disk, a floppy disk, or a semiconductor memory can be used as a storage medium. In addition, instead of the above-described embodiment, the condition for selecting the failure recovery method may be the job content of the higher-level device, the importance of a file in the storage device, or the like. A flexible failure recovery process can be performed by a combination of these conditions and a failure recovery method.

[0017]

According to the present invention, when the number of failed storage media is smaller than the redundancy of the storage device, normal read / write processing is given priority over recovery from the failure, so that the load on the storage device is heavy. In addition, it is possible to minimize a decrease in response performance in normal read / write processing. Further, when the margin of the redundancy is reduced, the normal read / write processing is automatically stopped and the priority is given to the processing of the failure recovery, so that the reliability of the storage device does not decrease. Further, since the failure recovery processing method is changed depending on the total of the failure recovery processing times of the respective failure storage media, a storage device with higher reliability can be realized. Further, since the frequency of the failure recovery processing or the ratio of the amount of failure recovery is set in accordance with the magnitude of the normal read / write processing frequency, the failure recovery processing can be executed efficiently in terms of time. As described above, according to the present invention, an appropriate failure recovery method can be selected in accordance with various conditions relating to the failure recovery, so that there is a remarkable effect that optimal failure recovery processing can be performed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of the present invention.

FIG. 2 is a configuration diagram of a storage device of the present invention.

FIG. 3 is a configuration diagram of a failure recovery table of a failed disk according to the present invention.

FIG. 4 is a flowchart showing a processing procedure of FIG. 2;

FIG. 5 shows a flowchart of a failure recovery processing selection block in FIG. 4;

FIG. 6 shows another flowchart of the failure recovery processing selection block in FIG.

FIG. 7 shows another flowchart of the failure recovery processing selection block in FIG.

FIG. 8 shows another flowchart of the failure recovery processing selection block in FIG.

FIG. 9 shows another flowchart of the failure recovery processing selection block in FIG.

[Explanation of symbols]

 150 I / O-fault recovery control circuit 154 fault recovery table 152 timer 156 fault data recovery recovery circuit 158 data disk # 0 160 data disk # 1 162 data disk # 2 164 data disk # 3 166 data disk # 4 168 data disk # 5 170 ECC data disk E1 172 ECC data disk E2 174 Spare disk S1 176 Spare disk S2

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-49449 (JP, A) JP-A-5-143471 (JP, A) US Patent 4,446,747 (US, A) (58) Fields studied (Int .Cl. ⁷ , DB name) G06F 3/06

Claims (11)

(57) [Claims] 1. A plurality of storage devices for storing a plurality of data groups and data for parity ticks of each data group of the plurality of data groups, and data stored in the defective data storage device.
Based on the data stored in the data storage device having no defect among the data groups to which the data belongs, and the parity tick data of the data group stored in the data storage device having no defect. A control device for performing a repair process.The control device monitors the occurrence of defects in the plurality of storage devices, and executes the repair process when the number of occurrences of the defect exceeds a preset value. A storage device characterized by being performed prior to other processing. 2. The control device according to claim 1, wherein the control device performs the repair process prior to other processes when the number of defective disks exceeds a preset value. Storage device. 3. A plurality of storage devices for storing a plurality of data groups and parity tick data of each data group of the plurality of data groups; a data storage device for storing restored data; When a failure occurs in any of the storage devices, the data stored in the failed data storage device is associated with data other than the data in the data group to which the data belongs, and And a control device for performing a restoration process based on the parity tick data and storing the restored data in a data storage device that accumulates the restored data. The storage device according to claim 1, wherein the restoration process is performed prior to an access request from a host unit in accordance with the number of the data storage devices. Place. 4. The control device according to claim 1, wherein, when the number of failed data storage devices is larger than a preset number, the control device performs the restoration process prior to an access request from a host unit. The storage device according to claim 3. 5. A plurality of storage devices for storing a plurality of data groups and parity tick data of each data group of the plurality of data groups; a data storage device for storing restored data; When a failure occurs in any of the storage devices, the data stored in the failed data storage device is associated with data other than the data in the data group to which the data belongs, and And a control device for performing a restoration process based on the parity tick data and storing the restored data in a data storage device that accumulates the restored data. If the number of failed data storage devices is greater than the preset number, the above-described restoration process is continued, and the number of failed data storage devices is increased. Is smaller than a preset number, the access from the host unit is permitted. 6. A plurality of storage devices for storing a plurality of data groups and parity tick data of each data group of the plurality of data groups; a data storage device for storing restored data; When a failure occurs in any of the storage devices, the data stored in the failed data storage device is associated with data other than the data in the data group to which the data belongs, and And a control device for performing a restoration process based on the parity tick data to be performed, and storing the restored data in a data storage device that stores the restored data. A storage device characterized in that the restoration process is performed prior to an access request from a host unit in accordance with a margin of redundancy of the storage device. apparatus. 7. The control device according to claim 1, wherein when the number of failed data storage devices is larger than a preset number, the control device performs the restoration process prior to an access request from a host unit. The storage device according to claim 6. 8. A plurality of storage devices for storing a plurality of data groups and parity tick data of each data group of the plurality of data groups; a data storage device for storing repaired data; When a failure occurs in any of the storage devices, the data stored in the failed data storage device is associated with data other than the data in the data group to which the data belongs, and And a control device for performing a restoration process based on the parity tick data to be performed, and storing the restored data in a data storage device that stores the restored data. If the number of failed data storage devices in the storage device is larger than a preset number, the restoration process is continued and the plurality of data storage devices are continued. If the number of failed data storage devices in the data storage device is smaller than a preset number, access from the host unit is permitted. 9. The storage device according to claim 1, wherein the control device stores the data restored by the restoration process in a spare storage device different from the storage device.
The storage device according to any one of the above. 10. A plurality of storage devices for storing data divided into bit units, byte units, or arbitrary units and parity tick data of the divided data, and one of the plurality of storage devices. Data for restoring the divided data having a defect stored therein based on the divided data stored in the other storage device having no defect and the data for parity ticks. Recovery means, monitoring means for monitoring the processing of the plurality of storage devices, and outputting a signal when any of the plurality of storage devices has a defect; and total number of the storage devices having the defect. Means for accumulating the data, and means for accumulating the number set based on the total number of the data for the parity ticks. If the number is larger than the set number, the repair is continued, and if the total number of the storage devices having the defect is smaller than the set number, the storage device can be accessed. Control means for controlling the storage device for temporarily suspending restoration of the divided data. 11. A plurality of storage devices that monitor processing of a plurality of storage devices that store data divided into bit units, byte units, or arbitrary units and parity tick data of the divided data, Detecting the defect generated in any of the above, determining the total number of the storage devices having the defect, and recovering the divided data stored in the storage device having the defect. When the repair frequency is set, and the total number of the storage devices having the defect is smaller than a predetermined value, the divided data is stored in the other storage device having no defect. Restoring based on the divided data and the data for parity ticks, storing the restored data in at least one of the storage devices; A first step of continuously restoring data; and a second step of temporarily suspending restoration of the divided data so that the storage device can be accessed. 2. The method of restoring data in a storage device according to claim 2, wherein the second step is executed based on the total number of the storage devices having the defect and the data restoration frequency.