JPH06119126A - Disk array device - Google Patents

Abstract

PURPOSE:To restart an interrupted data writing processing from its halfway point after the power source recovers and complete the processing even if a powder-down state is entered during the data writing processing on a disk array. CONSTITUTION:For the powder-down case, a nonvolatile memory 34 is stored with at least processing stage data 38 indicating the processing stages of a writing means 60 and a parity updating means 70 and new data 40 transferred from a host device 18. A restoring means 80, when power source is applied, refers to the processing stage data 38 in the nonvolatile memory 34, and performs restoration by using the new data 40 held in the nonvolatile memory 38 if the writing processing is interrupted halfway.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk array device in which a plurality of disk devices are accessed in parallel to perform data input / output processing, and more particularly, after power recovery from data held during power down during writing. The present invention relates to a disk array device to be restored for performing a data write recovery process. As external storage devices of computer systems, disk devices such as magnetic disk devices and optical disk devices, which have features such as non-volatility of recording, large capacity, and high speed of data transfer, are widely used. The requirements for the disk device are high-speed data transfer, high reliability, large capacity, and low price. A disk array device has been attracting attention as one that meets these requirements. A disk array device is a device in which a plurality of small disk devices are arranged, data is distributed and recorded in these devices, and accessed in parallel.

When data is transferred to a plurality of disk devices in parallel by a disk array device, it is possible to transfer data at a high speed that is twice as many as the number of disks as compared with the case of a single disk device. In addition to data, by recording redundant information such as parity data, it is possible to detect and correct data errors caused by disk device failure, etc., and duplicate the contents of the disk device. The same high reliability as the method of recording can be realized at a lower price than the duplication.

[0003]

2. Description of the Related Art Conventionally, David A. Passon of the University of California, Berkeley.
et al., published a paper that evaluated a disk array device that can access a large amount of data to many disks at high speed and realize data redundancy in the event of a disk failure, by classifying the disk array devices from level 1 to level 5. Announced (ACM SIGMOD Conferance, Chicago, Illi
nois, June 1-3, 1988 P109-P116).

Levels 1 to 5 for classifying the disk array device proposed by David A. Patterson and others are RA
ID (Redundant Arrays of In
abbreviated to "expensive Disks" 1 to 5. The RAID 1 to 5 will be briefly described as follows. [RAID0] FIG. 13 shows a disk array device having no data redundancy, which is not included in the classification of Debit A. Patterson et al.
Call it D0.

In the RAID 0 disk array device, as shown by data A to I, the disk array control device 10 distributes the data to the disk devices 32-1 to 32-3 based on the input / output request from the host computer 18. There is no data redundancy in the event of a disk failure. [RAID1] The RAID 1 disk array device is shown in FIG.
As shown in FIG. 4, the mirror disk device 32-2 stores the copies A ′ to D ′ of the data A to D stored in the disk device 32-1. RAID 1 is widely used because it has low utilization efficiency of a disk device but has redundancy and can be realized by simple control. [RAID2] A RAID2 disk array device strips data in units of bits or bytes,
Read and write in parallel to each disk unit. The striped data is physically recorded in the same sector in all disk devices. A Hamming code generated from the data is used as the error correction code. In addition to the data disk device, a disk device for recording the humming code is provided, and the failed disk device is specified from the humming code to restore the data.

By providing the redundancy by the hamming code as described above, correct data can be secured even if the disk device fails, but it has not been put into practical use because the utilization efficiency of the disk device is poor. [RAID3] A RAID3 disk array device has a configuration shown in FIG. That is, as shown in FIG. 16, for example, the data a, b, and c are divided into data a1 to a3, b1 to b3, and c1 to c3 in units of bits or sectors, and the parity P1 is calculated from the data a1 to a3. b1
To b3, the parity P2 is calculated, the parity c3 is calculated from the data c1 to c3, and the disk device 32- of FIG.
1 to 32-4 are simultaneously accessed and written in parallel.

In RAID 3, data redundancy is maintained by parity. Further, the data writing time can be shortened by the parallel processing of the divided data. However, all the disk devices 3 can be accessed with a single write or read access.
A parallel seek operation of 2-1 to 32-4 is required.
For this reason, it is effective when handling a large amount of data continuously, but in the case of transaction processing in which a small amount of data is randomly accessed, the high speed of data transfer cannot be utilized and efficiency decreases. [RAID4] As shown in FIG. 17, the RAID4 disk array device divides one data into sector units and writes the data in the same disk device. For example, the disk device 32
Looking at -1, the data a is divided and written into sector data a1 to a4. The parity is stored in the fixedly determined disk device 32-4. Here, data a1,
Parity P1 is calculated from b1 and c1, and data a2 and
Parity P2 is calculated from b2 and c2, and data a3 and
Parity P3 is calculated from b3 and c3, and data a4 and
Parity P4 is calculated from b4 and c4.

Data reading is performed by the disk devices 32-1.
32-3 can be read in parallel. Data a ~
To read b, taking the data a as an example, the disk device 3
2-1 sectors 0 to 3 are accessed to access sector data a1
To a4 are sequentially read and combined. For data writing, after reading the data and parity before writing and calculating and writing new parity,
A total of 4 accesses are required. For example, when updating (rewriting) the sector data a1 of the disk device 32-1, the old data (a1) _old of the update location and the corresponding old parity (P1) _old of the disk device 32-4 are read and new The operation of writing for a new parity (P1) _new that is consistent with the data (a1) _new is required in addition to writing data for updating.

Further, since the access is always made to the parity disk device 32-4 at the time of writing, it is impossible to simultaneously execute the writing to a plurality of disk devices. For example, even if the data a1 of the disk device 32-1 and the data b2 of the disk device 32-2 are simultaneously written, the parities P1 and P2 from the same disk device 32-4 are written.
Cannot be written at the same time because it must be read and written after calculation.

Although the definition of RAID4 has been made in this way, there are few merits and there are few movements for practical use at present. [RAID5] The RAID5 disk array device enables parallel reading and writing by not fixing the disk device for parity. That is, as shown in FIG.
The disk device in which the parity is placed is different for each sector. Here, from data a1, b1, c1 to parity P
1 is calculated, and the parity P is calculated from the data a2, b2, d2.
2 is calculated, and the parity P is calculated from the data a3, c3, d3.
3 is calculated, and the parity P is calculated from the data b4, c4, d4.
4 has been calculated.

For parallel reading and writing, for example, the disk device 3 is used.
2-1 sector 0 data a1 and disk device 32-2
Since the data b2 of sector 1 is located in the disk devices 32-4 and 32-3 having different parities P1 and P2, the data b2 does not overlap and can be read and written at the same time. Note that the overhead that requires a total of 4 accesses at the time of writing is RAI.
Same as D4.

As described above, RAID 5 is capable of asynchronously accessing a plurality of disk devices to perform read / write, and therefore is suitable for transaction processing for randomly accessing a small amount of data.

[0013]

However, in such a conventional disk array device, when the power supply is cut off for some reason during the data writing to the disk device, the conventional disk device or RAID 1 to In the disk array device up to RAID3,
While the same write operation could be performed again from the beginning after the power supply was restored, the same write operation could not be performed from the beginning again after the power supply was restored in the RAID4 and RAID5 disk array devices.

At the time of writing data of RAID4 and RAID5, the exclusive OR of the data in the plurality of disk devices is taken as the parity by the following equation (1), and the parity is held in the disk device for the parity. Data a (+) Data b (+) ... = Parity P (1) where (+) is the exclusive OR symbol data and the storage location of parity is RAID 4 in FIG.
It is fixed to the specific disk devices 32-1 to 32-4 as described above. On the other hand, in RAID 5, the parity is distributed to the disk devices 32-1 to 32-4 as shown in FIG. 18 to eliminate the concentration of access to a specific disk device due to the parity read / write operation.

At the time of reading these RAID4 and RAID5 data, since the data in the disk devices 32-1 to 32-4 are not rewritten, the integrity of the parity is maintained, but at the time of writing, the parity is also adjusted to the data. Need to change. For example, when one old data (a1) _old in the disk device 32-1 is rewritten to new data (a1) _new , the following formula (2) is calculated in order to obtain the consistency of the parity P1. By updating the parity, it is possible to maintain the parity consistency of the entire data of the disk device. Old data (+) old parity (+) new data = new parity (2) As can be seen from the equation (2), in the data writing process, it is necessary to first read the old data and the old parity in the disk device. Later, new data is written and new parity is generated and written. If the power is cut off while writing the new data or the new parity, it cannot be recognized how much the data is actually written normally, and the consistency of the parity is lost.

In this state, if the same data writing process is performed again when the power is restored, the old data and old parity are read from the disk device in which the parity is not consistent, so that the new inconsistent parity is generated. There was a problem that the writing work was ended. An object of the present invention is to provide a disk array device capable of resuming the data writing process interrupted after the power is restored and completing the data writing process even if a power down occurs during the data writing process.

Another object of the present invention is to allocate one data unit to each disk device and to allocate a parity to a disk array configuration in which the disk device is fixedly determined. There is provided a disk array device capable of being restarted from the middle and completed. Another object of the present invention is to allocate one data unit to each disk device and to allocate a parity to a disk array configuration in which the disk device is changed for each writing process. There is provided a disk array device which can be restarted from the above and completed.

Another object of the present invention is to make it possible to store the new data from the access processing stage and the host device in the non-volatile memory so that the data writing process interrupted after the restoration of the power supply can be resumed from the middle and completed. A disk array device is provided. Another object of the present invention is to provide a disk capable of storing new data and intermediate parity from a higher-level device in a non-volatile memory at the processing stage of access so that the data writing process interrupted after power restoration can be restarted from the middle and completed. An array device is provided.

Another object of the present invention is to make it possible to store the access processing stage, new data from the host device, intermediate parity and new parity in a non-volatile memory, and restart the data writing process interrupted after the power is restored. Provided is a disk array device that can be completed. Another object of the present invention is to supply backup power to an adapter of a disk device so that new data, old data, new parity, and old parity can be held in the adapter when the power is down, and data writing interrupted after the power is restored. Provided is a disk array device capable of restarting processing from the middle and completing the processing.

Another object of the present invention is to provide a disk array device in which the data writing process is restarted midway according to the access processing stage at the time of power down.

[0021]

FIG. 1 is a diagram for explaining the principle of the present invention. First, the present invention has the configuration shown in FIG. In FIG. 1A, the writing means 60 of the disk array mechanism stores the old data in the designated writing position of the arbitrary disk device 32-i when the writing process is instructed by the host device 18. After reading the data 42, the new data 48 transferred from the higher-level device 18 is written.

The parity updating means 70 is composed of the writing means 6
The old parity 44 is read from the storage position of the parity disk device 32-2 corresponding to the disk write position of 0, and the old parity 44, the old data 42 and the new data 40 are read.
Specifically, from the exclusive OR to the new parity 4
After generating 8, the new parity 48 is written in the disk storage position of the old parity 44.

Further, a non-volatile memory 34 is provided, and the non-volatile memory 34 stores the processing stage data 38 indicating the processing stages of the writing means 60 and the parity updating means 70 and the new data 40 transferred from the host device 18. To do. The restoration means 80 refers to the processing stage data 38 in the non-volatile memory 34 when the power is turned on, and if the writing process is interrupted midway, uses the new data 40 held in the non-volatile memory 34. Perform recovery processing.

Here, the parity updating means 70 includes a step of generating the intermediate parity 46 from the exclusive OR of the old data 42 and the old parity 44, for example. In the case of FIG. 1A, the processing mode of the recovery means 80 is one of the following two modes. [Mode 1] When the power down occurs before the writing of the new data (40) to the disk device is completed; in this mode 1, the data is stored in the writing position of the disk device 32-i designated by the writing means 60. After reading the old data 42, the new data 48 read from the non-volatile memory 18 is written, and after the writing of the new data 48 is completed, the parity updating means 70 sets the disk writing position by the writing means 60. The old parity 44 is read from the corresponding storage position of the parity disk device 32-2, and the new parity 4 is read based on the old parity 44, the old data 42, and the new data 40.
After generating 8, the new parity 48 is written in the disk storage position of the old parity 44.

[Mode 2] When the power supply is down before the completion of writing to the parity disk device 32-2 of the new parity; in the case of this mode 2, the disk device and the parity for writing the data by the writing means 60. The storage data of the corresponding position of the disk device other than the disk device for use,
Next, the read data of another disk device and the new data 4 read from the non-volatile memory 34 by the parity updating means 70.
After generating new parity 48 from 0 and old parity 4
The process of writing the new parity 48 into the disk storage position of No. 4 is performed.

In FIG. 1B, the intermediate parity (46) is further stored in the non-volatile memory 34, and a power down occurs from the completion of writing the new data 40 to the completion of the storage of the intermediate parity 46. The recovery process for when you add is added as a new mode. Further, as shown in FIG. 1C, the new parity 48 may be stored in the non-volatile memory 34,
For recovery after power down, processing from the next stage may be restarted based on the last stage data remaining in the non-volatile memory 34.

In this case, the disk devices 32-1 to 32-
Disk adapters 30-1 to 30-n provided for each n
Also, by adding a backup power supply, the old data 42 and the old parity 44 can be retained when the power supply is down, and re-reading at the time of restoration processing can be eliminated.

[0028]

According to the disk array device of the present invention having such a configuration, when a power down occurs in a disk array device having a configuration according to so-called RAID4 and RAID5, information stored in the nonvolatile memory is used. The writing process can be normally completed by restarting the process from the middle of the writing process, and the process from the beginning is not required after the power is restored, so that the restoration process can be performed at higher speed.

Further, the type of data to be retained for the recovery process due to the power down can be selected according to the available capacity of the non-volatile memory in terms of cost.

[0030]

2 is a block diagram of an embodiment showing a first embodiment of a disk array device according to the present invention. In FIG.
The disk array control device 10 is provided with a microprocessor (hereinafter referred to as “MPU”) 12. MPU1
ROM 20 storing control programs and fixed data in the internal bus 14 of No. 2, volatile memory 22 using RAM, cache memory 26 provided via the cache control unit 24, data transfer buffer 28, backup power supply 3
Non-volatile memory 3 that can operate even when the power is down due to 6
4 are connected.

Further, a host interface 16 is provided and is connected to a host computer 18 which functions as a host device. On the other hand, for the disk array control device 10, in this embodiment, six disk devices 32 are used.
-1 to 32-6 are provided, and the disk device 32-2 to
32-6 are device adapters 30-1 to 30
It is connected to the internal bus 14 of the MPU 12 via −6.

Of the six disk devices 32-1 to 32-6, four are for data storage, one is for parity, and the remaining one is a spare. Since the disk array device of the present invention realizes the same function as the RAID 4 shown in FIG. 17 or the RAID 5 shown in FIG. 18, if the disk device 32-6 is a spare disk device, for example, in the case of RAID4. Is a disk device 32-1
32-4 is used for data storage, and the disk device 32
-5 is used for parity.

On the other hand, in the case of RAID 5, each of the disk devices 32-1 to 32-5 stores the same data unit collectively in one disk device as in the case of RAID 4, but the disk device for parity. Is not fixed, and the disk device for parity is switched in a predetermined order every time the same storage position of the disk devices 32-1 to 32-5 changes.

FIG. 3 is a functional block diagram showing the processing contents in the first embodiment of FIG. In FIG. 3, n disk devices 32-1 to 32-n are used as an example of disk devices for the disk array control device 10.
It is assumed that the disk device 32-2 is used for parity. Of course, if the disk device 32-2 is RAID4, it is fixedly set for parity.
ID5 is positioned for parity in the current data access.

The disk array control mechanism 50 provided in the disk array control device 10 realizes the functions of the data writing unit 60, the parity updating unit 70, and the data restoring unit 80 under the program control of the MPU 12. A volatile memory 22 and a non-volatile memory 34 are connected to the disk array control mechanism 50. A device adapter 30-provided for each of the disk devices 32-1 to 32-n
It has a built-in memory for temporarily storing data exchanged with the disk devices 1 to 30-n.

In the first embodiment shown in FIG. 3, processing stage data 38 indicating the processing stages of the data writing unit 60 and the parity updating unit 70 is stored in the non-volatile memory 34, and transferred from the host computer 18. The new data 40 to be written in the designated disk device is stored. On the other hand, the volatile memory 22 stores the intermediate parity 46 and the new parity 48 generated by the processing of the parity update unit 70.

Further, the device adapters 30-1 to 30-
For n, for example, the device adapter 30-1 of the disk device 32-1 that is the target of data writing now
In this area, new data 40 transferred from the host computer 18 and old data 42 read from the new data writing scheduled area for updating the parity are stored. Further, the device adapter 30 of the disk device 32-2 for parity
In -2, the old parity 44 read from the same position corresponding to the new data writing scheduled area of the disk device 32-1 and the new parity 48 generated by the parity update unit 70 are stored.

Here, since all the memories used in the disk array control device 10 are non-volatile memories, the memory capacity increases and the cost is heavy. Therefore, in the first embodiment, the processing stage data 38 is used. The non-volatile memory 34 is allocated to store the new data 40 and the new data 40, and the volatile memory 2 is used for the other intermediate parity 46 and new parity 48.
I am using 2.

The host computer 1 when the power is down
If the new data 40 can be held on the eight side, the new data 40 may be stored in the volatile memory 22. FIG. 4 is a flowchart showing the overall processing operation in the disk array control mechanism 50 of FIG. In FIG. 4, first, when the disk array device is powered on, step S
In step 1, predetermined initialization is performed based on the initial program routine (IPL), and the process proceeds to step S2 to check whether or not the power supply is down. When the power is turned on by the logon after the power is turned off by the normal logoff operation, it is determined that the power is not turned off, and the process proceeds to step S3 to wait for the command reception from the host computer 18.

When the command from the host computer 18 is received in step S3, the process proceeds to step S4 to decode the command, and when the read access request is determined in step S5, the process proceeds to step S8 to execute the data read process, while the write operation is performed. When the access request is determined, the process proceeds to step S6 to execute the data writing process, and subsequently to the parity updating process in step S7.

On the other hand, when it is determined that the power source is down in step S2 when the power is turned on, the recovery process is performed in step S9, and then the normal process from step S3 is started. The data writing process of step S6 in the flowchart of FIG. 4 is performed by the data writing unit 60 provided in the disk array control mechanism 50 of FIG. 3, and the parity updating process of step S7 is performed by the parity updating unit 70. Further, the recovery process of step S9 is performed by the data recovery unit 80.

FIG. 5 is a flow chart showing details of the data reading process shown in step S8 of FIG. In FIG. 5, when the read command from the host computer is decoded, the data is read from the disk device via the device adapter that was the target of the data read, stored in the device adapter in step S2, and then stored in step S3.
Then, data is transferred to the host computer 18.

At this time, if the transfer rate on the side of the disk device and the transfer rate on the side of the host computer 18 are different, reading via the data transfer buffer 28 provided in the disk array controller 10 shown in FIG. The data is transferred to the host computer 18. Figure 6
4 is a flowchart showing details of the data acquisition process shown in step S6 of FIG.

In FIG. 6, since new data to be written to the disk device is transferred in response to the write command from the host computer 18, the new data 40 from the host computer 18 is stored in the memory, that is, the non-volatile memory 34 in step S1. To store. Subsequently, in step S2, if the new data 40 is designated as the writing target of the disk device 32-1, for example, the device adapter 30-1
And store it.

Then, the contents of the new data writing scheduled area of the disk device 32-1 are read as the old data 42 by the instruction from the device adapter 30-1, and the device adapter 3 is read.
Stored in 0-1. After storing the old data 42, the new data 4 in the device adapter 30-1 is stored in step S5.
0 is transferred to the disk device 32-1 and the new data 40 is written in the new data writing planned area in step S6.

FIG. 7 is a flow chart showing details of the parity update process shown in step S7 of FIG. Figure 7
First, in step S1, the contents of the same area as the new data write-scheduled area in the disk device 32-1 of the parity disk device 32-2 is read as the old parity 44, and in step S2, the read old parity 44 is read.
Is stored in the device adapter 30-2. Subsequently, in step S3, the intermediate parity 46 is created from the old data 42 and the old parity 44 and stored in the volatile memory 22.

Next, the new data 40 in the non-volatile memory 34 and the intermediate parity 46 in the volatile memory 22 are read to create a new parity 48, which is stored in the volatile memory 22.
Here, the intermediate parity 46 is created from the exclusive OR of the old data 42 and the old parity 44. Also, the new parity 48 is created from the same exclusive OR of the new data 40 and the intermediate parity 46.

When the new parity 48 is created and stored in step S4, the new parity 48 in the volatile memory 22 is read out and transferred to the device adapter 30-2 for storage in step S5. Subsequently, in step S6, the new parity 48 is transferred to the disk device 32-2 for parity, and in step S6.
In step 7, the new parity 48 is written in the same area as the new data write area in the disk device 32-1 of the disk device 32-2, and the parity update process ends.

Here, the new parity 48 is basically generated from the exclusive OR of the new data 40, the old data 42 and the old parity 44, but in the embodiment of FIG. The new parity 48 is created through the creation stage of the parity 46. There are the following three ways of creating a new parity through the steps of the intermediate parity 46, including the case of FIG. (1) The new data 40 and the old data 42 are exclusive ORed to generate an intermediate parity 46, which is stored in the volatile memory 22. When the storage in the volatile memory 22 is completed, the old data 42 becomes unnecessary, so the device adapter 30-
The memory area storing the old data of 1 is released.
Next, the new parity 48 is generated by exclusive ORing the intermediate parity 46 of the volatile memory 22 and the old parity 44 of the device adapter 30-2, and stored in the non-volatile memory 48.

That is, the processing of the following equation is performed. New data (+) Old data = intermediate parity Intermediate parity (+) Old parity = new parity (2) Exclusive OR of old data 42 and old parity 44 is generated to generate intermediate parity 46, which is stored in volatile memory 22. Store. When the storage of the intermediate parity 46 in the volatile memory 22 is completed, the old data 42 of the device adapter 30-1 and the old parity 4 of the device adapter 30-2 are stored.
The memory area storing 4 is released. Then, the intermediate parity 46 of the volatile memory 22 and the new data 40 of the non-volatile memory 34 are exclusive ORed to obtain the new parity 48.
Is generated and stored in the volatile memory 22. This is the processing of the embodiment of FIG. 3, and the processing of the following equation is performed. Old data (+) Old parity = intermediate parity Intermediate parity (+) New data = new parity (3) Old parity 44 stored in the memory of device adapter 30-2 and new data 40 of non-volatile memory 34
Then, the intermediate parity 46 is generated by exclusive ORing of the two, and stored in the volatile memory 22. When the storage of the intermediate parity 46 in the volatile memory 22 is completed, the old parity 44 becomes unnecessary, so that the memory area of the device adapter 30-2 in which the old parity 44 was stored is released.

Next, the intermediate parity 46 of the volatile memory 22.
And the old data 42 of the device adapter 30-1 are exclusive-ORed to generate a new parity 48 and the volatile memory 2
Store in 2. That is, the processing of the following equation is performed. Old parity (+) New data = intermediate parity Intermediate parity (+) Old data = new parity Further, generation of new parity via the intermediate parity generation stage is not limited to (1) to (3), and the device adapter 30 The read / storing of the old data 42 in −1 and the read / storing of the old parity 44 in the device adapter 30-2 may be selected in the order of speed (1) or (3).

That is, in the flow chart of FIG.
Although the parity update process is sequentially performed in step S7 after the data write process is performed in step S6, in reality, a seek instruction is issued to the disk device 32-1 to disconnect it, and then the parity update process is performed. Disk device 3
The seek command is issued to 2-2 and the two are separated, and the old data or the old parity is read out from the disk device 32-1 or 32-2 that receives the seek completion notification first.

Therefore, when the old data 42 is read out first, an intermediate parity is generated from the new data and the old data as shown in (1), and when the old parity 44 is read out first, (3). As described above, the intermediate parity is generated from the old parity and the new data, the new parity is generated when the old parity is read in the case of (1) after the generation of the intermediate parity, and the old data is read in the case of (3). When issued, you can just generate a new parity.

Of course, when the new data, the old data, and the old parity are gathered, new data (+) old data (+) old parity = new parity are collectively exclusive ORed to generate new parity. The process of generating the intermediate parity may be omitted.

FIG. 8 is a flow chart showing details of the restoration process shown in step S9 of FIG. Here, FIG.
In the first embodiment of the present invention, only the processing stage data 38 and the new data 40 are retained in the non-volatile memory 34 when the power is down. Therefore, the power down timing is the disk device of the new data 40. The contents of the restoration process are divided before and after the end of writing to 32-1.

In the recovery process of FIG. 8, first, step S
It is checked in 1 whether or not the writing of the new data is completed. If the writing of the new data is not completed, the power supply is down before the completion of the writing of the new data. Therefore, the process proceeds to step S2 and the subsequent steps. That is, in step S2, the new data 40 held in the non-volatile memory 34 is read out, transferred to the device adapter 30-1 and stored therein, and in the next step S3, the new data writing scheduled area from the disk device 32-1. Is read as the old data 42 and stored in the device adapter 30-1 in step S4.

Subsequently, in step S5, the device adapter 3
The new data 40 in 0-1 is transferred to the disk device 32-1 and the new data 40 is written to the disk device 32-1 in step S6. That is, when the power supply is down before the completion of writing the new data, the same processes as steps S2 to S6 except step S1 in the data writing process shown in FIG. 6 are executed as the recovery process. Since the new data 40 is held in the non-volatile memory 34 in this way, it is not necessary to transfer the new data 40 from the host computer 18 again at the time of the recovery process, and the recovery process can be speeded up accordingly.

Of course, when the writing of the new data 40 is completed in step S6, the parity update process is executed in step S7. This parity update processing is the same as the content shown in the flowchart of FIG. On the other hand, if it is determined in step S1 that the writing of new data has been completed, the process proceeds to step S8,
Check whether writing of new parity is completed. here,
If the writing of the new parity has not been completed, the processing from step S9 is performed. First, since the writing of the new data to the disk device 32-1 has already been completed, the disk device 32-2 for parity is used in step S9.
A new parity is created by the exclusive OR of the data read from the other disk devices 32-3 to 32-n except the new data and the new data. That is, the new parity is generated only from the new data and the data of another disk device without using the old parity.

Subsequently, in step S10, the new parity is transferred to the device adapter 30-2 and stored therein, and then transferred to the disk device 32-2 in step S11, and step S1.
In step 2, the new parity is written in the disk device 32-2, and a series of recovery processing is completed. Further, when it is judged in step S8 that the writing of the new parity is completed, the restoration process is not necessary, and therefore the process directly returns to the main routine.

FIG. 9 is a functional block diagram showing the processing contents of the second embodiment of the present invention. In the second embodiment, the processing stage data 38 and the new data 4 are stored in the non-volatile memory 34.
In addition to 0, the intermediate parity 46 is also stored. For this reason, the non-volatile memory 34 has a memory capacity increased by the amount of storing the intermediate parity 46, which makes the cost higher than that of the first embodiment. Can be further speeded up.

The overall control processing in the second embodiment of FIG. 9 is basically the same as that of the first embodiment shown in FIG. 4, and the processing by the data writing unit 60 and the parity updating unit 70 is also the intermediate parity. 6 and 7 except that 46 is stored in the non-volatile memory 34. On the other hand, the restoration process by the data restoration unit 80 becomes as shown in the flowchart of FIG. 10 as the intermediate parity 46 is newly stored in the nonvolatile memory 34.

In FIG. 10, the determination of the timing when the power supply is down is determined in steps S1, S8 and S13.
When it is determined in step S1 that the writing of new data has not been completed due to power down, the processes of steps S2 to S7 are performed. This is the same as the case of the first embodiment shown in FIG. Next, when it is determined in step S1 that the writing of the new data has been completed, it is determined in step S8 whether the storage of the intermediate parity has been completed. If the storage of the intermediate parity has not been completed, that is, if the power is down between the end of writing the new data and the storage of the intermediate parity, the processes of steps S9 to S12 are performed.

This processing is the same as the processing of steps S9 to S12 in the first embodiment of FIG. 8, and since the new data has already been written, it is read from another disk device other than the parity disk device. Create a new parity by taking the exclusive OR of the data and the new data,
Writing to the disk device for parity. Further, when it is determined in step S8 that the storage of the intermediate parity has been determined, the process proceeds to step S13 to check whether the writing of the new parity has been completed. If the writing of the new parity is not completed in step S13, that is, if the power-down occurs before the writing of the new parity after the storage of the intermediate parity is completed, the processes of steps S14 to S17 are performed.

First, in step S14, the nonvolatile memory 3
The new parity is created from the exclusive OR of the new data 40 held in No. 4 and the intermediate parity 46 and stored in the non-volatile memory 34. Next, in step S15, the new parity 48 is read from the non-volatile memory 34, transferred to the device adapter 30-2 and stored therein, and in step S15 the new parity 48 is transferred to the disk device 32-2, and in step S15.
Writing is performed at 17.

As described above, if the new data 40 and the intermediate parity 46 can be held in the nonvolatile memory 34 when the power is down, a new parity 48 is generated from the new data 40 and the intermediate parity 46 to generate a disk device for parity. 32-2
It is only necessary to write to, and the restoration process can be sped up compared to the case of starting over from the beginning. FIG. 11 is a block diagram of an embodiment showing the hardware configuration of the third embodiment of the present invention. In this embodiment, as shown in the nonvolatile memory 34 of the functional block diagram showing the processing contents of FIG. In addition to the processing stage data 38, the new data 40 and the intermediate parity 46, the new parity 48 is also held.

Further, the backup power supply line 52 from the backup power supply 36 is connected to the device adapters 30-1 to 30-3.
0-6, all the device adapters 30-1 to 30-6 are activated when the power is turned off, the recovery data 42 and the old parity 44 read from the disk device side are held, or the disk array control mechanism 50 is used. It is characterized in that the new data 40 and the new parity 48 transferred from the side can be held.

According to the third embodiment shown in FIGS. 11 and 12, when the processing is interrupted when the power is down, the data obtained immediately before the interruption is the non-volatile memory 34 and the device adapters 30-1, 30. -2 is retained as it is, so the recovery process after the power is restored can be restarted from the stage immediately before the stage where the power down occurred, and the duplicated process before and after the power down can be minimized. The high-speed restoration processing can be performed.

In the above embodiment, the magnetic disk device was used as an example of the disk device, but it is needless to say that a disk array of an optical disk device may be used instead.

[0069]

As described above, according to the present invention, even if the power supply goes down during the writing process of the disk array having the configuration corresponding to RAID4 and RAID5, the writing process is restarted halfway after the power is restored. By doing so, it is possible to complete the writing process while maintaining the data redundancy, and it is possible to further improve the reliability of the disk array device.

Further, by holding the data stored in the non-volatile memory, the recovery process after power-down can be sped up, and the device can be started up more quickly.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is an example configuration diagram showing a hardware configuration of a first example according to the present invention.

FIG. 3 is a functional block diagram showing the processing contents of FIG.

FIG. 4 is a flowchart showing the overall processing operation of the first embodiment.

FIG. 5 is a flowchart showing details of the data reading process of FIG.

FIG. 6 is a flowchart showing details of the data writing process of FIG.

FIG. 7 is a flowchart showing details of the parity update process of FIG.

FIG. 8 is a flowchart showing details of the recovery process of FIG.

FIG. 9 is a functional block diagram showing the processing contents of the second embodiment of the present invention.

FIG. 10 is a flowchart showing details of recovery processing in the second embodiment.

FIG. 11 is an example configuration diagram showing a hardware configuration of a third example according to the present invention.

FIG. 12 is a functional block diagram showing the processing contents of the third embodiment.

FIG. 13 is an explanatory diagram of a RAID 0 disk array device.

FIG. 14 is an explanatory diagram of a RAID 1 disk array device.

FIG. 15 is an explanatory diagram of a disk array device based on RAID3.

FIG. 16 is an explanatory diagram of data division in RAID3.

FIG. 17 is an explanatory diagram of a disk array device using RAID4.

FIG. 18 is an explanatory diagram of a RAID 5 disk array device.

[Explanation of symbols]

 10: Disk array control device 12: MPU 14: Internal bus 16: Host interface 18: Host computer (upper device) 20: ROM 22: Volatile memory (RAM) 24: Cache control unit 26: Cache memory 28: Data transfer buffer 30-1 to 30-n: Device adapter 32-1 to 32-n: Disk device 34: Nonvolatile memory 36: Backup power supply 38: Processing stage data 40: New data 42: Old data 44: Old parity 46: Intermediate parity 48: New parity 50: Disk array control mechanism 52: Backup power line 60: Writing means (data writing section) 70: Parity updating means (parity updating section) 80: Restoration means (data restoration section)

Claims (18)

[Claims] 1. An upper device after reading old data (42) stored at a write position of a designated disk device (32-i) when a writing process is instructed by the upper device (18). From the writing means (60) for writing the new data (48) transferred from (18) and the storage position of the parity disk device (32-2) corresponding to the disk writing position by the writing means (60) The old parity (44) is read, and the old parity (4
4), parity updating means for writing the new parity (48) in the disk storage position of the old parity (44) after generating the new parity (48) based on the old data (42) and the new data (40) ( 70), the writing means (60) and the parity updating means (70)
Non-volatile memory (34) for storing processing stage data (38) indicating the processing stage of No. 1 and new data (40) transferred from the upper device (18), and processing of the non-volatile memory (34) when the power is turned on. With reference to the stage data (38), if the writing process is interrupted midway, a restoration means (80) for performing the restoration process using the new data (40) held in the non-volatile memory (34). ), And a disk array device comprising: 2. The disk array device according to claim 1, wherein the parity updating means (70) is configured to use old data (4).
2), a new parity (48) is generated from the exclusive OR of the old parity (44) and the new data (40). 3. The disk array device according to claim 2, wherein the parity update means (70) excludes two of the old data (42), the old parity (44) and the new data (40). An intermediate logical parity (46) is generated from the logical OR, and a new logical value is obtained from an exclusive logical OR of the intermediate parity and the remaining one of the old data (42), the old parity (44) and the new data (40). A disk array device characterized by generating a parity (48). 4. The disk array device according to claim 1, wherein the recovery means (80) writes a new data (40) to the disk device when a power down has occurred before the completion of writing to the disk device. Write the new data (48) read from the non-volatile memory (34) after reading the old data (42) stored in the write position of the disk device (32-i) designated by the inserting means (60). Then, the parity update means (70) reads the old parity (44) from the storage position of the parity disk device (32-2) corresponding to the disk write position by the write means (60). , Old parity (44), old data (4
2) and new parity (4) based on new data (40)
A disk array device, characterized in that, after generating 8), a process of writing the new parity (48) in the disk storage position of the old parity (44) is performed. 5. The disk array device according to claim 1, wherein said recovery means (80) is set to a power-down state before the completion of writing to the parity disk device (32-2) of the new parity. Causes the writing means (60) to read the stored data at the corresponding position of the disk device other than the disk device for writing the new data (40) and the parity disk device, and then the parity updating means. After the new parity (48) is generated from the read data of the other disk device and the new data (40) read from the non-volatile memory (34) by (70), it is stored in the disk storage position of the old parity (44). A disk array device characterized by causing a process of writing new parity (48). 6. An upper device after reading old data (42) stored at a write position of a designated disk device (32-i) when a writing process is instructed by the upper device (18). From the writing means (60) for writing the new data (48) transferred from (18) and the storage position of the parity disk device (32-2) corresponding to the disk writing position by the writing means (60) The old parity (44) is read and the old parity (44) is read.
After generating the intermediate parity (46) from the old data (42) and the old parity (44), the new parity (48) is generated from the intermediate parity (46) and the new data (40). ), A parity updating means (70) for writing in the disk storage position, and the writing means (60) and the parity updating means (70).
Non-volatile memory (34) for storing processing stage data (38) indicating the processing stage of the new data, new data (40) transferred from the host device (18), and intermediate parity (46).
When the power is turned on, the process stage data (38) of the non-volatile memory (34) is referred to. If the writing process is interrupted midway, the new data stored in the non-volatile memory (34) is stored. Data (40) and intermediate parity (46)
A disk array device comprising: a recovery unit (80) for performing recovery processing using the. 7. The disk array device according to claim 6, wherein said parity updating means (70) excludes two of said old data (42), old parity (44) and new data (40). An intermediate logical parity (46) is generated from the logical OR, and a new logical value is obtained from an exclusive logical OR of the intermediate parity and the remaining one of the old data (42), the old parity (44) and the new data (40). A disk array device characterized by generating a parity (48). 8. The disk array device according to claim 6, wherein the recovery means (80) writes the new data (40) to the disk device if the power down has occurred before the completion of writing to the disk device. Write the new data (48) read from the non-volatile memory (34) after reading the old data (42) stored in the write position of the disk device (32-i) designated by the inserting means (60). Then, the parity update means (70) reads the old parity (44) from the storage position of the parity disk device (32-2) corresponding to the disk write position by the write means (60). , Old parity (44), old data (4
2) and the new data (40) to generate the intermediate parity (46) and then the new parity (48), and then write the new parity (48) to the disk storage position of the old parity (44). A disk array device characterized by performing the following. 9. The disk array device according to claim 6, wherein the restoration means (80) writes the new data (40) to the non-volatile memory (34) of the intermediate parity (46). When the power supply is down before the storage, the writing means (60) reads the stored data at the corresponding position of the disk device other than the disk device for writing the new data (40) and the parity disk device. Then, the parity update means (70) reads the data from the other disk device and the non-volatile memory (34).
New data (40) read from and new parity (4
A disk array device, characterized in that, after generating 8), a process of writing the new parity (48) in the disk storage position of the old parity (44) is performed. 10. The disk array device according to claim 6, wherein said restoration means (80) has an intermediate parity (46).
If the power down occurs after the storage of the data and before the completion of writing the new data (40), the parity update means (7
0) the new data (40) and the intermediate parity (46) are read from the non-volatile memory (34) to generate a new parity (48), and then the new parity (48) is stored in the disk storage position of the old parity (44). ) Is performed, a disk array device characterized by performing the process of writing. 11. An upper device after reading old data (42) stored at a write position of a designated disk device (32-i) when a writing process is instructed by the upper device (18). From the writing means (60) for writing the new data (48) transferred from (18) and the storage position of the parity disk device (32-2) corresponding to the disk writing position by the writing means (60) The old parity (44) is read, and the old parity (4
4), parity updating means for writing the new parity (48) in the disk storage position of the old parity (44) after generating the new parity (48) based on the old data (42) and the new data (40) ( 70), the writing means (60) and the parity updating means (70)
A non-volatile memory (34) for storing processing stage data (38) indicating the processing stage of No. 3, new data (40) transferred from the host device (18), and new parity (48); The processing stage data (38) of the non-volatile memory (34), if the writing process is interrupted midway, new data (40) and new parity (40) held in the non-volatile memory (38) are stored. 48) A disk array device comprising a recovery means (80) for performing recovery processing using the above. 12. The disk array device according to claim 11, wherein said parity updating means (70) converts said old data (42) and old parity (44) into intermediate parity (4).
6) is generated, new parity (48) is generated from the intermediate parity and new data (40), and the non-volatile memory (3) is generated.
4) also stores the intermediate parity (46), and the restoration means (80) further includes new data (40) and intermediate parity (46).
A disk array device, wherein recovery processing is performed by using the new parity (48). 13. The disk array device according to claim 12, wherein said parity updating means (70) comprises said old data (42), old parity (44) and new data (40).
The intermediate parity (46) is generated from the exclusive OR of the two, and the intermediate parity and the remaining one of the old data (42), the old parity (44) and the new data (40). A disk array device characterized by generating a new parity (48) from an exclusive OR. 14. The disk array device according to claim 11, further comprising the disk devices (32-1 to 32-n).
A disk array device characterized in that backup power is supplied to the disk adapters (30-1 to 30-n) provided for each, and old data (42) and old parity (44) can be held when the power is down. 15. The disk array device according to claim 1, wherein said non-volatile memory (34) has a backup power supply. 16. The disk array device according to claim 1, wherein the plurality of disk devices (32-1 to 32-3).
Each of 2-n) receives writing of the same data belonging to one data unit, and uses a predetermined disk device for storing parity, a disk array device. 17. The disk array device according to claim 1, wherein the plurality of disk devices (32-1 to 32-3).
Each of 2-n) receives writing of the same data belonging to one data unit, and a different disk device is used for storing parity for each data writing. 18. A disk array device according to claim 1, wherein said writing means (60) and parity updating means (70) are operated in parallel.