JP2742186B2 - Disk driver, disk array device, data storage system, and data backup method for disk array system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system having a predetermined number of data storage devices such as a disk drive, and more particularly to a backup of data stored in the storage devices.

[0002]

2. Description of the Related Art A disk array device is disclosed, for example, in Japanese Patent Application Laid-Open No. 1-250128. The feature of this device is that high speed is realized by simultaneous multiplex operation of a plurality of disk drives, and high reliability is realized by having redundant disk drives and spare disk drives.

In order to speed up a disk drive,
Although it is necessary to increase the data transfer speed and improve the number of read / write processes per second (IO throughput), in a disk array device, data is transferred to a plurality of disk drives in parallel. By making it possible, the data transfer speed is increased. A configuration in which redundancy described later is added to such a configuration in order to increase reliability is generally called RAID3. Also,
In order to improve IO throughput, there is a configuration in which a plurality of disk drives are made to wait for multiple seeks / rotations. A configuration in which redundancy is added to such a configuration to increase reliability is called RAID5. I have.

[0004] In order to improve the above performance, a plurality of disk drives are required in any of the above configurations. The mean time to failure (MTBF) of a current standard disk drive is about 50,000 hours, and the mean time to failure (MTBF) in a disk array device using N disk drives is 50,000 / MT.
It can be reduced to N hours. However, this value is the standard 10
In the case of a disk array device having a unit configuration, the time is 5,000 hours, that is, less than seven months, which is generally unacceptable for a system.

In order to solve this problem, the disk drives of the disk array device are divided into groups consisting of several data disk drives and one parity disk drive, and the data is divided into data units called stripes. Then, a group called a parity group is formed by all stripes starting from the same logical address in all the disk drives in the group, and the parity information is calculated by calculating an exclusive OR of all data stripes in the parity group. Is known, and this is stored as a parity stripe in a parity disk drive of the parity group. Such a configuration is called a RAID, and is not limited to simply distributing data to a plurality of disk drives. Even if any one of the parity groups fails, the parity information stored in the parity disk drive is not changed. The data of the failed disk drive can be recovered, and the reliability is improved.

The mean time to failure of a RAID (MT
BF) is expressed by the following equation (1).

[0007]

(Equation 1)

According to the above equation (1), the time required for replacing a failed disk drive with a normal disk drive and recovering data to this disk drive, that is, the average repair time (MTTR) of the disk drive, is the average failure time (MTTR).
It can be seen that this is an important factor for determining BF). In order to minimize the mean time to repair (MTTR), a spare disk drive to be replaced with a failed disk drive is provided in the parity group in advance, and when a failure occurs, the spare disk drive is used immediately by using the spare disk drive. It is effective to perform recovery. Such a spare disk drive is also disclosed as a spare disk drive in the above-mentioned JP-A-1-250128.

By employing the RAID configuration and the spare disk drive, the problem of a decrease in the mean time to failure (MTBF) in a disk array device including a plurality of disk drives can be solved.

[0010]

However, the mean time to failure (MTBF) expressed by the above equation (1) is based on the assumption that failure events of a plurality of disk drives in the system are independent of each other. This does not take into account the case of a large-scale disaster such as an earthquake or fire, or the case of a double failure due to a mistake during the recovery work. Also,
No consideration has been given to data loss due to operational errors.

There is no practical method for solving such a problem other than regular backup of data. In the above-mentioned conventional technology, an effective backup method corresponding to an increase in capacity due to the arraying of disk drives. The method is not considered. In fact, the standard 5.2
When a 5 "disk drive (1.5 GB) is used, a parity group is formed by ten such disk drives, and one of them is assigned to a spare disk drive and the other is assigned to a parity disk drive. , The total capacity of this parity group is 10 GB,
Standard backup tape drives (for example, 10
0 kbytes / sec or about 200 kbytes / sec
The time required for backup in c) is less than 14 hours. This is a major obstacle when applied to an online transaction system utilizing the high IO throughput of the disk array device. This is because when performing data backup every day, the service of the system must be stopped for the last 14 hours to perform the backup operation.

An object of the present invention is to solve such a problem, to greatly reduce the occupation time of data backup, and to effectively perform data backup, a disk drive, a disk array device, and data storage. An object of the present invention is to provide a data backup method for a system and a disk array system.

It is another object of the present invention to provide a disk drive, a disk array device, a data storage system, and a data backup system for a disk array system, which can perform effective data backup without interrupting system services. It is to provide a method.

[0014]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a method for storing data in place of a fault information storage device when a fault occurs in an information storage device for storing data. The spare storage device as the information storage device is a data transfer buffer between the information storage device and the data backup device when the data is backed up.

Further, the present invention has means for recording access information to the file system to be backed up on the information storage device which is backed up by the data backup device, and based on the access information, While the host computer accesses the file system to be backed up, data of the file system to be backed up can be backed up.

Further, according to the present invention, in a disk driver having a semiconductor memory for temporarily storing data read from a disk, a first means for setting a predetermined portion of a recording area of the disk as a write-protected area, A second means for dividing the storage area of the semiconductor memory into a plurality of parts and managing the divided areas, wherein one or more storage areas of the semiconductor memory divided and formed by the second means are set by the first means. The data read from a part or all of the written write protected area is recorded and saved, and thereafter, the write protected area of the disk is made writable.

[0017]

An information storage device for storing data (file) used by a host computer and parity information calculated from the data, and a storage device arranged on an array in the computer system. There is a spare storage device for logically replacing the failure information storage device when a failure occurs. In the present invention, such a backup storage device is used as a data transfer buffer between the information storage device and the data backup device when backing up data in the information storage device.

According to this, even if the data transfer speed of the data backup device is sufficiently lower than the data transfer speed of the information storage device, the data transfer speed from the information storage device to the data transfer buffer is high. The data transfer to the data transfer buffer is performed at a high speed, and therefore, the time required for data backup is very short for the information storage device.

An 8 mm tape drive or data D which is currently generally used as a large-capacity data backup device
The data transfer rate of an AT (Digital Audio Tape Recorder) device is about 200 kB / sec, and the data transfer rate of a disk drive is about 3 MB / sec. is there. Therefore, by buffering the data transfer to the backup device by the spare disk drive, the occupation time for data backup in the disk drive can be reduced to 1/10 or less. In the case of the prior art described above, the occupation time of a disk drive for data backup, which took about 14 hours in the past, can be reduced to 1.4 hours or less. This means that in a system that performs data backup once a day, the system downtime for this backup is reduced from 14 hours per day to 1.4 hours.

Further, according to the present invention, since the access information to the file system to be backed up on the information storage device backed up by the data backup device can be recorded, the file system to be backed up can be stored in the host computer. After the file system is accessed, the file system can be transferred to the data backup device. Therefore, even if access is made during data backup, the file system after access can be backed up.

Further, in the present invention, the area to be backed up in the recording area of the disk is set as a write-protected area, and data read from this write-protected area is temporarily stored in a semiconductor memory and saved. When all data is read from this write-protected area and saved in the semiconductor memory, the write-protection of this area is released, and normal external data writing becomes possible. The data saved in the semiconductor memory is transferred to the backup device. Therefore, the data transfer from the disk to the semiconductor memory is performed at high speed even if the data backup transfer time, which is the time required from the time when the data on the disk is read until the data is finally transferred to the backup device, is sufficiently long. Even if the write-protection is set, it is released in a short time, so that the occupation time of the data backup is short.

[0022]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a disk array device, a data storage system, and a data backup method of a disk array system according to the present invention, wherein 1 is a host computer, 1-1 is a CPU (central processing unit), -2 is a main storage unit, 1-3 is an I / O buffer, 1
-4 is an I / O (input / output) controller, 1-5 is a disk I
/ F (interface), 1-6 is an OS (operating system), 1-7 is a file management unit, 1-8 is a device driver, 2 is a disk array controller,
2-1 is a host I / F, 2-2 is a CPU, 2-3 is a data transfer control device, 2-4 is a parity generation / check unit,
2-5 is a transfer buffer, 2-6-1, 2-6-1, 2-
6-3, 2-6-4 are drive I / Fs and 3-1 and 3 respectively.
−2, 3-3 are backup devices, respectively, 4-1 and 4-2
Is a spare disk drive, 5 is a data / parity disk drive, 6, 7-1, 7-2, 7-3, 7
-4 are SCSI (Small Computer System Interface)
e) It is a bus.

In FIG. 1, a host computer 1, a disk array controller 2, and a backup device 3-
1 are connected to each other by a SCSI bus 6, and the disk array controller 2 has SCSI buses 7-1 and 7-
Disk drives are connected in an array by 2,..., 7-3. Of these disk drives, S
The disk drives connected to the CSI buses 7-1, 7-2,... Are the data / parity disk drives 5, among which the SCSI buses 7-1, 7-2,.
The disk drive connected to one of the... Is the parity disk drive described above, and the rest are data disk drives. Also, the disk drive connected to the SCSI bus 7-4 is replaced with the spare disk drive 4-
1,4-2, ... These SCSI buses 7-1,
7-2,..., 7-3 have the same number of disk drives, and the SCSI buses 7-1, 7-2,.
.. (That is, the data / parity disk drives 5 arranged in a row in the horizontal direction in the drawing) constitute the above parity groups, and each parity group is connected to the SCSI bus 7-3. Spare disk drives 4 are added one by one.

Incidentally, instead of the backup device 3-1,
Any one of the SCSI buses 7-1 to 7-3 or a separate SCSI bus 7-4 for the disk array controller 2.
And a backup device 3-3 or 3-2
May be provided.

The above disk array controller 2, disk drives arranged in an array, and a backup device constitute a disk array device.

The host computer 1 is an I / O for buffering and caching input / output data to / from the disk drive 5, etc.
I / O which is a hardware having a buffer 1-3 and controlling input / output of data to / from a main storage unit 1-2 and a disk drive 5 for temporarily storing data and instructions used by the CPU 1-1. Control unit 1-4 (a recent workstation uses a dedicated processor for the I / O control unit 1-4, reduces the load on the CPU 1-1 for input / output processing of data to a disk drive, etc. A disk I / F 1 for performing interface control with the disk array controller 2.
-5 and OS1-6. Data input / output processing to / from a secondary storage device such as the data / parity disk drive 5 is managed by software such as a module 1-7 of the OS 1-6 and a module such as a device driver 1-8. These determine the scheduling of data input / output with the data / parity disk drive 5 requested by the application program, buffering, access data length, and the like.

In this embodiment, each interface (I / F) is SCSI. SCSI is ANSI
(American National Standard Institute), ISO (International Standard Organization)
However, it is an approved interface for computer peripherals and supports not only magnetic disk drives but also optical disk drives, magnetic tape devices, printers, scanners, etc., and is widely used in small computers.

The disk array controller 2 has a drive I / F 2-6-1, 2-6-2,..., 2-6.
3 to control the data / parity disk drives 5 and the spare disk drives 4 arranged in an array, so that the host computer 1 looks as if one normal disk drive is connected. Data sent from the host computer 1 is a host I / F 2
-1 and distributed to the data / parity disk drives 5 arranged in an array via the data transfer control unit 2-3 and the transfer buffer 2-5 according to the logical address. When there is a data request from the host computer 1, the data transfer control unit 2-3, the transfer buffer 2-5
The data distributed from the host I / F 2-1 to the data / parity disk drives 5 arranged in an array via the host I / F 2-1 are integrated and transferred to the host computer 1.

In the disk array device, even if one data / parity disk drive 5 fails in the same parity group, the data is sent from the host computer 1 so that the data can be recovered there. Incoming data is added with redundant data (that is, parity information) and stored in a parity disk drive among the data / parity disk drives 5. The generation and check of the parity information are performed by the parity generation / check unit 2-4. When the data / parity disk drive fails, an operation is performed on the parity information stored in the parity disk drive in the parity group and the data of the non-failed data disk drive, and the data of the failed data / parity disk drive is replaced. It is generated by this calculation and stored in the spare disk drive 4 for this parity group. When all the data on the failed data disk drive has been recovered and stored in the spare disk drive 4, the spare disk drive will occupy the logical position of the failed data disk drive and will be replaced by the failed data disk drive. Is a data disk drive.

In this way, even if a failure occurs in the data disk drive, the data can be automatically and promptly recovered without manual intervention. The spare disk drive is not used in a normal case where no failure of the data disk drive occurs.

Backup device 3-1, 3-2 or 3
-3 is for backing up data stored in the disk array device. As described above, in the disk array device, even if any one data disk drive fails in one parity group, no data is lost, but multiple data disk drives fail simultaneously in the same parity group. When multiple failures occur, or when data is accidentally erased due to an operator error, data is lost. The backup device 3-1, 3-2 or 3-3 is provided to prevent such a situation, and backs up the same data stored in the disk array device. When the above failure occurs, the data in the backup device is sent to the disk array device (recovery of the backup data) so that it can be used. As such a backup device, a storage device of a replaceable medium having a low cost per storage capacity such as a magnetic tape device or a magneto-optical disk drive is mainly used. In recent years, a large-capacity device such as a 5 GB magnetic tape device has been developed.

The operation of this embodiment will be described below. (1) When Host Computer 1 Recognizes Spare Disk Drive and Backup Device: FIG. 2 is a diagram showing a logical configuration as viewed from the host computer 1 in this case.

In this figure, reference numeral 2 denotes a data / parity disk whose disk array is controlled and controlled by the disk array controller 2 in FIG. 1 and which appears to the host computer 1 as a single disk drive. This is a conceptual representation of the whole array of the drives 5 and is referred to as a disk array. The buffer disk 8 conceptually represents the spare disk 4 (generally, a plurality) shown in FIG. From the host computer 1, these are the backup devices 3 (the backup devices 3-1 and 3- in FIG. 1).
2, 3-3) and one SCSI bus
It looks as shown in FIG. 2 as a device having an ID. The SCSI bus ID is an address allocated to each device for distinguishing a plurality of devices connected on the SCSI bus.

In the above configuration, the host computer 1
Recognizes the buffer disk 8 as one SCSI bus device, and can perform all necessary transfers for backup under its own management. However, it is needless to say that it is not always necessary to manage all of them.

Data transfer for backing up data in the disk array 2 to the backup device 3 is performed from the disk array 2 to the buffer disk 8 (1).
And transfer (2) from the buffer disk 8 to the backup device 3. As a preferred example, the transfer (1) is performed by the host computer 1 while recognizing the file structure of the disk array 2, and the transfer (2) is a method in which the host computer 1 intervenes only for the start instruction and the end confirmation. According to this, the host computer 1 can perform normal access to the disk array 2 during the transfer (2).

For example, in the case of a UNIX machine, TA
The transfer to the buffer disk 8 is performed using the R command. At this time, the buffer disk 8 is accessed as a RAW device. When the data is transferred by the TAR command, the format is the same as when the data is backed up to a normal MT device. Therefore, in the data transfer (2), the range to be transferred from the host computer 1 to the buffer disk 8 and even the transfer destination are specified at the time of startup do it. However, for this purpose, the buffer disk 8 is set to the SCSI bus command 1
COPY command must be supported.

In the above transfer (1), the host computer 1 intervenes from the start to the end of the transfer because of (a) processing of an open file, (b) determination of an area where data to be backed up exists, and (c) disk. The above data format and normal backup device (such as a magnetic tape device. These are usually sequential access devices, which have a format different from the magnetic disk which is a random access device). This is because the transfer (1) can be performed using only the supported commands. When the transfer (1) is performed without the intervention of the host computer 1, as described later, a), b), and
It is necessary to support the processing, the command for determination, and the message of c).

However, as shown in FIG. 1, although the disk array controller 2 is actually one SCSI bus device, the disk array controller 2 and the buffer disk 8 in FIG. You have to play a double role. Although such a configuration does not exist in the SCSI bus protocol, implementation is possible.

(2) When the host computer 1 recognizes the backup device but does not recognize the spare disk device: FIG. 3 is a logical configuration diagram viewed from the host computer in this case, and a portion corresponding to FIG. Have the same reference numerals.

Here, the buffer disk 8 in FIG. 2 is not recognized by the host computer 1. In this case, the data transfer from the data / parity disk drive 5 to the spare disk drive 4 corresponding to the above data transfer (1) is managed by the disk array controller 2 including the activation and termination processing. In this case, the backup may be performed using a normal backup command (in the above example, the TAR command). Nevertheless, by temporarily buffering in the spare disk drive 4, there is an effect that the time during which the data / parity disk drive 5 can be used for normal access is increased.

The host computer 1 reads the data in the disk array 2 to read the file management information necessary for the backup, but the host computer 1 reads the data in the disk array 2 to transfer the data to the backup device 3. Without reading data, SCSI bus COP
There is a method of backing up data in the disk array 2 using a Y command. When the COPY command is received, the spare disk drive 4 is used as a data transfer buffer, and the disk array controller 2 performs control, so that higher-speed backup can be performed.

In the backup processing in the disk array controller 2, there are three preferred examples shown in FIGS. 4, 5, and 6, depending on the physical connection position of the backup device 3.

FIG. 4 shows the backup device 3 as a host I / F
FIG. 5 shows a case where the connection is made to the SCSI bus 6 on the side of FIG.
Is drive I to which no other disk drive is connected
/ F2-6, and FIG. 6 shows a case where it is connected to the drive I / F2-6 to which the spare disk drive 4 is connected. 4 to 6, each of the data / parity disk drive 5 and the spare disk drive 4 is shown one by one. Of course, as shown in FIG. FIG. 2 conceptually shows a disk array controller 2 that is collectively controlled like a single disk drive.

In the case of the example shown in FIG. 4, the host computer 1 reads the file management information of the area of the data / parity disk drive 5 to be backed up and reads the file management information from the data / parity disk drive 5 to the backup device 3.
A command instructing transfer to the disk array controller 2 is issued to the disk array controller 2 (the transfer may be performed by the host computer 1). The disk array controller 2 temporarily transfers data whose destination is the backup device 3 to the spare disk drive 4, and then transfers the data from the spare disk drive 4 to the backup device 3. As a result, the time that the data / parity disk drive 5 is occupied for backup can be reduced.

In the case of the example shown in FIG. 5, the backup device 3 is connected to the drive I / F of the disk array controller 2.
2-6, data is transferred from the spare disk drive 4 to the backup device 3 by the host I / O.
This is performed without passing through the SCSI bus 6 on the F2-1 side. For this reason, the deterioration of the access performance from the host computer 1 to the data / parity disk drive 5 during the backup is small.

However, in this case, in order to make the host computer 1 think that the backup device 3 is connected as shown in FIG. Access must be passed transparently. This means that the buffer disk 8 in FIG.
Similarly to the above, the method is not specified in the SCSI bus protocol, but can be implemented.

In the example shown in FIG. 6, the backup device 3 is connected to the same SCSI bus as the spare disk drive 4. In this case, the data transfer from the spare disk drive 4 to the backup device 3 is performed without passing through the inside of the disk array controller 2. For this reason, the host computer 1 further backing up to the data / parity disk drive 5 Access performance degradation can be prevented. This effect is maximized when the spare disk drive 4 supports the COPY command.

(3) When the Host Computer 1 Recognizes Neither the Backup Device nor the Spare Disk: FIG. 7 is a conceptual configuration diagram viewed from the host computer 1 in this case. As the actual physical connection, similar to the case where the backup device 3 is recognized, three types shown in FIGS. In this case, since the host computer 1 does not recognize the backup device 3, the disk array controller 2 must support a backup command. It should be noted that such a command is not specified by the SCSI bus, but such a command can be implemented as a vendor unique. In order to perform a backup, the host computer 1 first reads the file management information of the backup target area, and issues an address to be backed up and a command instructing the backup to the disk array 2 in the order of the backup.

(4) When a 2-port SCSI bus disk drive is used: In each of the embodiments described above, a normal 1-port disk drive is assumed. However, in all of the above embodiments, a configuration using a two-port SCSI bus disk drive is also conceivable. One embodiment is shown in FIG. The feature of this embodiment is that the data transfer from the data / parity disk drive 5 to the spare disk drive 4 and the command / message transfer from the normal host computer 1
The point is that the access to the parity disk drive 5 does not conflict with the SCSI bus. Spare disk drive 4
When the backup device 3 is connected to the position shown by the dotted line, the data transfer from the host computer 1 to the backup device does not conflict with the access from the host computer 1 to the data / parity disk drive 5, and the backup is not performed. Low performance degradation during operation.

(5) Method of Backing Up Without Closing System: In the embodiment described above, the time for occupying the disk drive for the backup could be reduced. The file system or partition that is backing up must have at least one set of files and its area during processing of the management information in order to prevent loss of data integrity and consistency with management information during backup. Write access to the system must be stopped (system blockage). However, the use of online transactions may require a 24-hour service, and such a system cannot tolerate such a blockage.

In order to perform backup without blocking the system, the following procedure may be followed. That is, 1) The file opened in the disk area to be backed up during the backup is recorded. The recording destination may be on a disk or a memory. The list of open files generally exists on the main storage of the host computer. 2) The target area is backed up to the backup device including the open file (of course, may be omitted). 3) If the file was a backup target area when the file was closed, the backup is performed in an area continuous with the backup performed in 2) in the same manner as in the differential backup.

Instead of 1), all write accesses after the file open processing are recorded, and the area without write access is backed up even if it is open, and only the area with write access is closed. After the processing, a differential backup may be performed.

FIG. 9 is a block diagram showing an embodiment of a disk drive according to the present invention.
I bus, 9a and 9b are SCSI control units, 10 is a memory control unit, 11 is a data memory, 12 is a format control unit, 13 is a read / write amplifier (hereinafter referred to as R / W amplifier), 14 is a magnetic head, 15 is a recording disk,
16 is a write-protected area determination unit, 17 is a spindle motor,
Reference numeral 18 denotes a VCM, and 19 denotes a battery.

In FIG. 9, the SCSI control unit 9a
The protocol control of the SI bus 8a is performed, and the SCSI controller 9b controls the protocol of the SCSI bus 8b.
The memory control unit 10 controls data transfer between the SCSI control units 9a and 9b, the data memory 11, and the format control unit 12, and as shown in FIG.
Is divided into four storage areas and managed. Data memory 1
1 preferably has a capacity of at least several tracks of the disk 15, and here, the capacity is 1 Mbyte. The data memory 11 uses a battery 19 to make data non-volatile. The format control unit 12 manages a sector division method of a recording track on the disk 15. The R / W amplifier 13 has a disk 15
When data is recorded on the disk 15, the magnetic head 14 is driven by the data.
4 is amplified and converted into a digital signal. The write-protected area determination unit 16 determines whether or not the data write scheduled area on the disk 15 is a write-protected area, and if it is a write-protected area, stops the write operation of the format control unit 12.

Next, the operation of this embodiment for backing up data in a predetermined area of the recording area on the disk 15 will be described with reference to FIG.

The data backup operation includes a lock command for saving the backup area in the data memory 11 and a backup read command for transferring the data saved in the data memory 11 to an external backup device. The instruction is executed by the disk drive receiving a type of instruction from a host device (not shown).

When the disk drive receives a partial lock command from the host device (step 101), the disk drive 1
5 temporarily sets the lock area designated by this partial lock instruction as a write-inhibited area (step 102), and secures an area in the data memory 11 for temporarily saving data in the lock area (step 102). 103). The data memory 11 is normally in a state shown as “normal time” in FIG. 10. However, if there is a partial lock instruction, if the capacity of the lock area is 3/4 or less of the capacity of the data memory 11, the data in the lock area FIG. 1 shows the minimum area in which
The status is set to any one of “at the time of evacuation 1”, “at the time of evacuation 2”, and “at the time of evacuation 3” shown in FIG. If the capacity of the lock area exceeds 3/4 of the capacity of the data memory 11, the data memory 11 is set to the state of "evacuation 3" in FIG. 10 and data having a capacity equal to 3/4 of the capacity of the data memory 11 is stored. The data is read from the lock area, stored in the save areas of the second to fourth areas of the data memory 11 (step 104), and the writing of the lock area of the disk 15 that has been read is permitted (step 105). If all data in the lock area cannot be stored in the save area of the data memory 11 (step 10).
6) Notify the SCSI controller 10 of the completion of the partial lock (step 107). If all the data in the lock area can be stored in the save area of the data memory 11 (step 106), when the save of the lock target area is completed,
It is notified that writing is possible (step 108).

Thereafter, upon receiving a backup read command (step 109), the disk drive sets the SCSI bus to which the backup read command has been transferred to the S bus.
The backup data is transferred from the save area of the data memory 11 to the host device via one of the CSI buses 8a and 8b (step 110). Upon receiving the notification of the completion of the backup data reception from the host device (step 11)
1) If the disk drive has finished transferring all the backup data in the backup area specified by the partial lock command to the host device (step 11).
2) Return the save area set in the data memory 11 to the normal area (step 113), release the partial lock state on the disk 15 (step 114), and complete the backup operation.

If the untransferred portion remains in the backup area (step 112), the process continues to step 10
A series of operations 4 to 112 are performed, and the data in the remaining lock area is saved to the data memory 11 (step 1).
04) and transfer to the host device (step 110) are repeated.

After the steps 107 and 108,
When there is no backup read instruction (step 10
9) When a read command to disk 15 is received (step 120), normal read processing is performed and disk 1
5 (step 122), if it is a write-protected area (step 124), writing is prohibited (step 126), but if it is not a write-protected area, normal write processing is performed (step 12).
5). If neither a read nor a write instruction is received, processing of another instruction is performed (step 123).

As described above, in this embodiment, after the backup data is saved in the data memory 11,
It is possible to suppress a decrease in the throughput of the disk drive for data write operation and backup for the disk 15.

FIG. 12 is a block diagram showing still another embodiment of the disk array device according to the present invention in which the disk drives described in FIGS. 9 to 11 are arranged on an array. Is a disk array device, 22 is a host interface control unit (hereinafter referred to as host I / F), 23 is a data distribution control unit, 24 is a buffer memory as a cache memory, 25 is a parity generation unit, 26 is a data recovery unit, 27 is a magnetic tape device control unit (hereinafter, referred to as MT control unit), 28 is a magnetic tape device (hereinafter, referred to as MT device), 29a to 29e are S
The CSI control units 30a to 31e and 32 are the disk drives (hereinafter referred to as HDDs) described with reference to FIG.
Is a SCSI control unit.

In FIG. 12, the host I / F 22 receives commands and write data from the host computer 20 to the disk array device 21,
From the CPU to the host computer 20. The data distribution control unit 23 controls data transfer between the host I / F 22, the cache memory 24, the parity generation unit 25, the data recovery unit 26, the MT control unit 27, and the SCSI control units 29a to 29e, 33, and 34. Do. Further, the data distribution control unit 23
At the time of data writing, the write data from the host computer 20 is divided into data blocks (the previous data stripes) in units of 4 kbytes and distributed to the HDDs 31a to 31e.
The data blocks from 31e are collectively reconstructed into read data to the host computer 20.

Each data block is written as follows. That is, now, the data is four data blocks D0
If the data block D00 is divided into 0, D01, D02, and D03, as shown in FIG.
a, the data block D01 in the HDD 30b, the data block D02 in the HD 30c, and the data block D03.
Are sequentially arranged in the HDD 30d.
0e, these data blocks D00, D01, D0
2, a parity block P0 generated from D03 is arranged. The next data is data blocks D10, D11, D
Assuming that the parity block is P1 and these parity blocks are P1, these are also stored in the HDDs 30a to 30e, but the parity block P1 is stored in the HDD 30d. In the same manner, sequential data is stored. It should be noted that the data blocks divided from the same data and the parity blocks generated by them are collectively referred to as a parity group, as described above.

The parity block is generated by the parity generation unit 13.
However, as shown in the following Expression 2, 4 of the same parity group
It is generated by exclusive ORing two data blocks.

[0066]

(Equation 2)

The cache memory 12 temporarily stores write data and read data. The data recovery unit 14 is for recovering the lost data block by using the normal data block and the parity block in the parity group when the data block in the parity group is lost due to the failure of the HDD. It is. For example, when the HDD 30a breaks down, as shown in the following equation 3, the data block D0 is used by using the data blocks D01, D02, D03 and the parity block P0.
You can recover 0.

[0068]

(Equation 3)

SCSI controllers 29a-29e, 33, 3
Reference numeral 4 controls the protocol of the SCSI bus to which the HDD is connected. The MT control unit 27 controls the MT device 28 as a backup device, and records data from the HDD on a magnetic tape in the MT device 16 for backup. The HDDs 30a to 31e and 32 can be connected to two SCSI buses. The HDD 33 is for a spare.

The data recording / reproducing operation of this embodiment will be described below with reference to FIG. 14. First, data from the host computer 20 is transferred to the D00 area of the HDD 30a and the HDD 30a.
The case of recording in the D01 area of 30b will be described.

When a write command and write data are transmitted from host computer 20 at time t01, host I / O
F22 transfers these write commands and write data to the data distribution control unit 23. At time t02, the data distribution control unit 23 transfers the write data to the cache memory 24, and generates
It requests data reading from the control units 29a, 29b and 29e. Therefore, the SCSI control unit 29a requests the HDD 30a to read the data block D00, the SCSI control unit 29b requests the HDD 30b to read the data block D01, and the SCSI control unit 29e requests the HDD 30e to read the parity block P0.

At time t03, the HDDs 30a, 30b, 3
0e reads a data block and a parity block of the same parity group, respectively,
These data blocks are transferred to a, 29b and 29e. Therefore, the SCSI controllers 29a, 29b, 29e
Transmits these read data blocks to the data distribution control unit 2.
3 and the data distribution control unit 23 stores them in the cache memory 12.

Here, the read data block and the parity block from the HDDs 30a, 30b, 30e are rd0, rd1, rp0, respectively, and the data blocks of the write data from the host computer 20 are wd0, w
Let it be d1.

At time t04, the data blocks rd0 and rd1, the parity block rp0, and the data blocks wd0 and wd1 are transferred from the cache memory 24 to the parity generation unit 25. In the parity generation unit 25, a new parity block wp0 is
Is generated and transferred to the cache memory 24.

[0075]

(Equation 4)

At time t05, the data distribution control unit 23
The write command and the write data blocks wd0 and wd1 and the parity block wp0 are sent to the SCSI controllers 29a, 29b and 29e, respectively. As a result, the SCSI control unit 29a requests the HDD 30a to write the data block wd0 to the recording area D00, and the SCSI control unit 29b
Is the recording area D0 of the data block wd1 in the HDD 30b.
1, the SCSI controller 29e requests the HDD
A request is made to 30e to write the parity block wp0 into the recording area P0.

At time t06, the HDDs 30a, 30b, 3
0e write operation is completed by the SCSI control units 29a, 29
b, 29e to the data distribution control unit 23,
Thereby, the data distribution control unit 23 sets the host I / F 2
2, the host computer 20 is notified of the completion of the write command. Thus, the data recording operation ends.

Next, for example, when the SCSI controller 29b or the SCSI bus connected to it fails,
The operation of reproducing data from the D00 area of the DD 30a and the D01 area of the HDD 30b will be described.

Now, assuming that such a failure has occurred at time t10, the SCSI control unit 29b notifies the data distribution control unit 23 of this. Thereafter, assuming that a read command is transmitted from the host computer 20 at time t11, the host I / F 22 transfers the read command to the data distribution control unit 23. At time t12, the data distribution control unit 23
Requests the SCSI controller 29a to read the HDD 30a. Further, the data distribution control unit 23 checks the faulty SC
Instead of the SI controller 29b, the SCSI controller 33
Request reading of DD 30b.

At time t13, the HDDs 30a and 30b
The read data block is transferred to the data distribution control unit 23 via the SCSI control units 29a and 33, respectively. Therefore, the data distribution control unit 23 supplies the data blocks from the HDDs 30a and 30b and transmits the data blocks to the host computer 20. Thus, the data reproduction operation ends.

Next, the data recovery operation of this embodiment will be described with reference to FIG.
5 will be described. Assuming that the HDD 30a has failed at the time t20, the HDD 30a detects the
This is notified to the data distribution control unit 23 via the control unit 29a. At time t21, the data distribution control unit 23 requests the data recovery unit 26 to recover the data blocks in the HDD 30a to the spare HDD 32. Data recovery unit 26
At time t22, via the SCSI control unit 33,
30b to 30e, the data block D01, D02, D03 and parity block P of the first parity group
Request a read of 0.

From time t23, data recovery unit 26 sets H
Receiving the read data from the DDs 30a to 30e, the operation of the above equation 2 is sequentially executed to recover the data block D00. Then, at time t24, when the transfer of the blocks D01, D02, D03, and P0 of the first parity group and the data recovery operation are completed, the data recovery unit 26 sets
The recovered data block D00 is written to the spare HDD 32 via the SI control unit 33. At time t24, when the writing to the spare HDD 32 is completed,
The data recovery unit 26 is notified via the control unit 33. The data recovery unit 26 notifies the data distribution control unit 23 of the recovery completion of the data block D00, and permits access to the data block D00. Subsequently, recovery processing is sequentially performed on other data blocks.

At time t26, the data recovery unit 26 completes the recovery operation of the last data block Dk0, and
The recovered data block Dk0 is written to the spare HDD 32 via the control unit 33. Then, at time t27, the spare HDD 32 notifies the data recovery unit 26 of the write completion via the SCSI control unit 33. Data recovery unit 26
Notifies the data distribution control unit 23 that all data blocks have been recovered, and the data recovery process is completed.

In the above data recovery processing, the SCS
Since the I control units 29a to 29e are not used, data blocks can be written / read in parallel to the HDDs 31a to 31e other than the parity group of the failed HDD 30a even during the data recovery processing.
Reading is possible at 0e.

Next, the data backup operation of this embodiment will be described with reference to FIG. Assume that at time t30, the host computer 20 issues a partial backup instruction for the area of the data blocks D12 to D53 in the disk array device 21. Therefore, the data distribution control unit 23
Via the CSI control units 29a to 29e, the HDDs 30a to
Requests partial lock of data blocks D12 to D53 to 30e, and prohibits reception of a write request from host computer 20 to such an area. Since each HDD has the 1-Mbyte data memory 11 (FIG. 9) as described above,
All the data in the lock area can be stored and saved in the save area of the data memory 11, and when the saving of each block in the lock target area is completed, it is notified that writing is possible in the area. In this example,
One parity group can save up to 3840 kbytes of data.

Next, at time t32, the SCSI controller 20
a to 20e notify the data distribution control unit 23 of the completion of the partial lock of the HDD, whereby the data distribution control unit 23 notifies the SCSI control unit 33 of the HDDs 30a to 30e.
Requesting the transfer of the backup data from the client to the MT device 28. Further, if all the backup areas specified by the host computer 20 can be stored in the data memory 11 in the HDDs 30a to 30e, the host computer 20 is permitted to accept a write request to this area.

At time t33, the SCSI controller 33 requests the HDD 30c to read the first data block D12 of the partial backup. Upon receiving the data block D12, the SCSI control unit 33 sends the data block D12 to the MT control unit 27 at time t34, and requests the MT device 28 to write. Accordingly, the MT control unit 27 starts writing the data block D12 to the MT device 28.

The SCSI control unit 33 controls the data block D
12 is completed, at time t35, the HDD 30d
To read the data block D13, and before the writing of the data block D12 to the MT device 28 is completed, the next data block D13 is read to the SCSI control unit 33 in advance. At time t36, when there is a write completion notification of data block D12 from MT control unit 27, SCS
The I control unit 33 notifies the HDD 30c of the completion of the reception of the data block D12.

Subsequently, the SCSI control unit 33 issues a request to write the read data block D13 to the MT device 28 and a request to read the data block D20 from the HDD 30a. At time t37, when the write completion notification of the data block D13 is received from the MT control unit 27,
The SCSI control unit 33 notifies the HDD 30d of the completion of the reception of the data block D13, and notifies the data distribution control unit 23 of the end of the backup of the data block of the parity group in the first column.

Similarly, at time t38, when a write completion notification of data block D23 is received from MT control unit 27,
The SCSI control unit 33 notifies the data distribution control unit 23 of the end of the backup of the data block of the parity group in the second column. At time t39, when receiving the write completion notification of the data block D53 at the end of the backup area from the MT control unit 27, the SCSI control unit 33 instructs the data distribution control unit 23 to end the backup of the data block of the parity group in the second column. Then, at time t40, the host computer 20 is notified of the completion of the partial backup.

The case where the backup area can be completely saved in the data memory 11 (FIG. 9) in the HDD has been described above. However, when the backup area is larger, the data distribution control unit 23 sets the disk 15 (FIG. 9). In the backup area of (1), acceptance of a write request from the host computer 20 is permitted from the area saved in the data memory 11.

As described above, the SCSI controllers 29a to 29e are not used for transferring the backup data.
Access to 30a to 31e is possible.

In this embodiment, since a bus used for data recovery and data backup is provided in addition to a normal HDD access bus, performance degradation due to occupation of the bus for data recovery or data backup is prevented. be able to. Further, since the bus used for data recovery and data backup is also used for the spare HDD, there is no need to provide a separate SCSI control unit for controlling the spare HDD 32, and the cost can be reduced accordingly.

In this embodiment, since one parity group is connected by one bus, the data blocks distributed to a plurality of HDDs in the parity group can be read only by sequentially reading the HDDs. You can reorder them in their original order.

[0095]

As described above, according to the present invention,
The occupation time of the data disk during backup can be reduced by the ratio of the transfer speed of the backup device to the magnetic disk drive (typically, the magnetic tape device is about 200 kB / sec, whereas the magnetic disk drive has 3 MB / sec, which is about 1/15).

Further, according to the present invention, an open file in the backup target area is recorded, and the closed file is backed up again, so that the backup can be performed without closing the system.

Further, according to the present invention, the backup data is saved in a part of the semiconductor memory in the disk drive, and is transferred to the backup device between normal disk accesses. The drive can be prevented from being occupied for a long time. In addition, since the area of the backup area of the disk where the data saving has not been completed is write-protected, the data written there is not accidentally destroyed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a disk array device, a data storage system, and a data backup method for a disk array system according to the present invention.

FIG. 2 is a configuration diagram showing a specific example of a logical connection as viewed from a host computer in the embodiment shown in FIG. 1;

FIG. 3 is a configuration diagram showing another specific example of the logical connection as viewed from the host computer side in the embodiment shown in FIG. 1;

FIG. 4 is a diagram showing a specific example of processing on the disk array controller side in the logical connection shown in FIG. 3;

5 is a diagram showing another specific example of the processing on the disk array controller side in the logical connection shown in FIG. 3;

FIG. 6 is a diagram showing still another specific example of the processing on the disk array controller side in the logical connection shown in FIG. 3;

FIG. 7 is a configuration diagram showing still another specific example of the logical connection as viewed from the host computer side in the embodiment shown in FIG. 1;

FIG. 8 is a block diagram showing another embodiment of the disk array device, the data storage system, and the data backup method of the disk array system according to the present invention.

FIG. 9 is a block diagram showing one embodiment of a disk drive according to the present invention.

FIG. 10 is a diagram showing a state during a data backup operation of the data memory in FIG. 9;

FIG. 11 is a flowchart showing an operation at the time of data backup in the embodiment shown in FIG. 9;

FIG. 12 is a block diagram showing still another embodiment of the disk array device using the disk drive shown in FIG. 9 according to the present invention.

13 is a diagram showing a data write state in each disk drive in FIG.

FIG. 14 is a timing chart showing data write and data read operations of the embodiment shown in FIG.

FIG. 15 is a timing chart showing a data recovery operation in the embodiment shown in FIG.

FIG. 16 is a timing chart showing an operation at the time of data backup in the embodiment shown in FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Disk array controller 3 Backup device 4 Spare disk drive 5 Data / parity disk drive 6 Host side SCSI bus 7 Drive side SCSI bus 10 Memory control unit 11 Data memory 12 Format control unit 15 Disk 16 Write protected area judgment unit Reference Signs List 20 host computer 21 disk array device 23 data distribution control unit 24 buffer memory 25 parity generation unit 26 data recovery unit 28 magnetic tape device 29a to 29e SCSI control unit 30a to 30e, 31a to 31e disk drive 33, 34 SCSI control unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoto Matsunami 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. Microelectronics Devices Development Laboratory (72) Inventor Shoichi Miyazawa Yoshida, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture 292 Hitachi, Ltd. Microelectronics Device Development Laboratory (72) Inventor Soichi Isono 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Microelectronics Device Development Laboratory

Claims (20)

(57) [Claims] 1. A disk array controller, a disk drive connected to the disk array controller by a drive interface for storing a plurality of data arranged in an array, etc., and a data stored in the disk drive. A data backup device for backing up, one or more disk drives of the plurality of disk drives as spare disk drives, the rest as data / parity disk drives for storing data and the like, In a disk array device that uses a data / parity disk drive instead of the failed data / parity disk drive, the backup disk drive and the data / parity disk drive are used when backing up data. The disk array apparatus, characterized in that the data transfer buffer between the backup device. 2. The disk array device according to claim 1, wherein the data backup device is connected to a drive interface of the disk array controller so as to be controllable from the disk array controller. 3. The disk array device according to claim 2, wherein the data / parity disk drive has two or more interfaces and is connected to the disk array controller and the data backup device. 4. The information processing apparatus according to claim 1, wherein the information indicating the recognition result is obtained from a means for recognizing a current use range of the file system on the plurality of disk drives arranged on the array or a host computer. Means for backing up data in the use range of the file system to the data backup device without the intervention of the host computer, and transferring the data to the plurality of disk drives arranged on the array. A disk array device for recovering backup data of a data backup device. 5. The system according to claim 4, further comprising: means for recognizing an address changed from the time of the previous backup or means for acquiring information representing the result of the recognition from the upper computer, wherein the upper computer intervenes. A differential backup to the data backup device, and recovery of backup data of the data backup device to the plurality of disk drives arranged on the array. 6. The means according to claim 1, wherein access to the file system to be backed up on the plurality of disk drives arranged on the array, which is being backed up to the data backup device, is recorded. A disk array device, characterized in that data of the file system to be backed up can be backed up while accessing the file system to be backed up from a host computer. 7. A computer system connected by one or more interfaces, and a plurality of storage devices connected to each of one or more drive interfaces, so that the plurality of storage devices can store file data. In the data storage system, at least one of the storage devices is a spare storage device, and when a failure occurs in the storage device that stores the data, when the failure occurs in the storage device that stores the data, instead of the failed storage device, Means for occupying the logical position with the spare storage device; and means for using the spare storage device as a data transfer buffer between the storage device and the backup means at the time of data backup of data in the storage device. A data storage system comprising: 8. The method according to claim 7, wherein: a means for recognizing a current use range of the file system on the plurality of storage devices or a host computer.
Means for acquiring information representing the recognition result, progress of backup of the data in the usage range of the file system to the data backup means, without intervention of the higher-level computer, and on the plurality of storage devices A data backup system for recovering backup data of the data backup means. 9. The method according to claim 8, further comprising: means for recognizing an address changed from the time of the previous backup or means for acquiring information representing the result of the recognition from the higher-level computer, wherein the higher-level computer intervenes. A differential backup to the data backup means, and recovery of backup data of the data backup means to the plurality of storage devices. 10. The computer according to claim 7, further comprising: a unit that records access to the file system to be backed up on the plurality of storage devices that are being backed up to the data backup unit. A data storage system capable of backing up data of the file system to be backed up while accessing the file system to be backed up. 11. A disk array controller, a disk drive connected to the disk array controller by a drive interface for storing a plurality of data and the like arranged in an array, and a disk drive for storing data stored in the disk drive. A data backup device for backing up, one or more disk drives of the plurality of disk drives as spare disk drives, the rest as data / parity disk drives for storing data and the like, In a disk array system in which a data / parity disk drive is used in place of the failed data / parity disk drive, the backup disk drive is replaced with the data / parity disk drive when backing up data. Data backup method for a disk array system characterized by a data transfer buffer between the data backup device. 12. The data backup method according to claim 11, wherein the data backup device is controlled by the disk array controller. 13. The data backup method according to claim 11, wherein the disk drive has two or more interfaces and is connected to the disk array controller and the data backup device. 14. The apparatus according to claim 11, wherein information representing a result of the recognition is obtained from a means for recognizing a current use range of the file system on the plurality of disk drives arranged on the array or a host computer. The backup of data in the range of use of the file system to the data backup device without the intervention of the host computer, and the backup of the data backup device to the plurality of disk drives arranged on the array. A data backup method for a disk array system, wherein backup data is recovered. 15. The system according to claim 14, wherein information indicating a result of the recognition is obtained from a means for recognizing an address changed from the time of a previous backup or from the host computer, and the data is obtained without intervention of the host computer. A data backup method for a disk array system, wherein a differential backup to a backup device is progressed, and backup data of the data backup device is recovered to the plurality of disk drives arranged on the array. 16. The file system according to claim 14, wherein access to the file system to be backed up on the plurality of disk drives arranged on the array on which backup to the data backup device is being executed is recorded. A data backup method for a disk array system, wherein data of the file system to be backed up can be backed up while accessing the file system to be backed up from a host computer. 17. A disk driver having a semiconductor memory for temporarily storing data read from a disk, a first means for setting a predetermined portion of a recording area of the disk to a write-protected area, and recording of the semiconductor memory. A second means for dividing the area into a plurality of areas and managing the divided areas, wherein a write-protection set by the first means is set in one or a plurality of storage areas in the semiconductor memory divided and formed by the second means. A disk driver which records data read out from a part or all of an area and saves the data, and thereafter, enables writing in a recording area which is a write-protected area on the disk. 18. The disk driver according to claim 17, wherein a plurality of means for connecting to a host device are provided. 19. A disk array device comprising a plurality of disk drivers and an array control device according to claim 17 or 18, wherein data backup of said disk driver is performed under the control of said array control device. A disk array device for setting the write-protection area for a data backup area and performing a data saving operation to the semiconductor memory. 20. The storage medium according to claim 19, wherein a plurality of paths are provided for connecting the disk driver and the array control device, and the connection path for transmitting a command to set the write-protected area and a save operation and the backup data. A disk array device, wherein the connection path for transferring data from the set write-protected area of the disk device to the semiconductor memory is separated.