JPH09212425A - Write cache backup system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent data in a cache memory from being lost in case of a power source fault by writing the data in the cache memory to a backup disk and transferring data which can not be backed up from a nonvolatile memory to a host system as information. SOLUTION: When a host system 1 makes a write instruction, data are written in the cache memory 32 of a disk controller 3 through a host-side control part 31. The disk controller 3 instructs writing to the cache memory 62 to a device side control part 63 of the disk controller 6 through a drive-side bus and the data in the cache 32 are copied to the cache memory 62. If the contents of the cache memory 62 are altered, the device side control part 63 backs up the contents of the cache memory 62 on the backup disk 8 through a backup bus 7 and stores backup information on the cache memory 62 in the nonvolatile memory 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write cache backup system for backing up cache memory data in a disk controller provided with a write back type write cache.

[0002]

2. Description of the Related Art FIG. 2 is a system configuration diagram when a disk controller having a conventional write-back type write cache function is connected to a host system. The host system 1 and the host system 1 and the disk control device 3 that controls the reading or writing of host data to the disk drive are connected by a host-side bus 2. The disk control device 3 includes a host-side control unit 31 that controls data transfer with the host system, a cache memory 32, and a device-side control unit 33 that controls data transfer on the device side. Disk drives 51-53
Is connected to the disk controller 3 via the device-side bus 4, and the data of the host system 1 is recorded. The disk drives 51 to 53 are daisy chain connected to the disk control device 3 by the device-side bus 4.

When the disk controller 3 is instructed to write data from the host system 1, the host-side control unit 31 causes the host-side control unit 31 to store data transferred via the host-side bus 2 in the cache memory 32 as soon as the data is stored in the cache memory 32. The access time is improved by returning the write completion status to the host system 1 via the side bus 2 and not writing to the disk drives 51-53 at that time. The data written in the cache memory 32 is written in the disk drives 51 to 53 when the cache memory 32 overflows or in response to an instruction from the host system 1.

[0004]

In the above-mentioned disk device, when the data writing operation is performed, the data writing is completed in the cache memory and the data is not actually written in the disk drive. In the case of the failure of 1), there is a problem that the data which has not been written in the disk drive is lost, and the reliability is remarkably lowered. Further, when a power failure occurs, the host system must transfer all the data that has been written, and it is necessary to transfer the data that has not been written, and it takes time to restore the data.

[0005]

In order to solve the above-mentioned problems, the write cache backup system according to the present invention uses a write cache backup system for daisy chain connection of a plurality of disk controllers and each disk controller with a host system. A non-volatile memory for recording backup information of the cache memory in at least one disk controller among the device side bus, a plurality of disk controllers, a disk drive for backing up the contents of the cache memory, and a backup disk It has a backup bus for connecting the drive and the disk controller.

More specifically, the write cache backup system of the present invention is a host-side bus for daisy-chaining a plurality of disk controllers having a write-back write cache function and each disk controller with a host system. And a device-side bus for daisy-chaining each disk controller and disk drive, and for backing up the contents of the non-volatile memory and the cache memory that store the backup information of the cache memory in the connected disk controller. At least one disk controller having a disk drive for backup and a backup bus for connecting the disk drive for backup and the disk controller, and a write operation from the host system is performed and stored in the cache memory. Data is transferred to the cache memory of another disk controller via the device-side bus for copying, the copied data is written to the backup disk drive via the backup bus, and information that could not be backed up is non-volatile. Transfer from memory to host system as information.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram of a write cache backup system according to an embodiment of the present invention. The disk control devices 3 and 6 control reading or writing of host data from the host system 1 to the disk drive. The disk control device 3 and the disk control device 6 are daisy chain connected to the host system 1 by the host side bus 2.
The disk controller 3 has a cache memory 32, and the disk controller 6 has a cache memory 62. The host-side control unit 31 controls data transfer with the host system by the disk control device 3. The host-side control unit 61
The disk controller 6 controls data transfer with the host system. The disk drives 51 to 53 are connected to the disk control device 3 and the disk control device 6 and record data of the host system 1.

The device side bus 4 is a disk drive 5
1 to 53 are the disk control device 3 and the disk control device 6
Connect with and transfer data. Disk drive 51-
53 is daisy chain connected to the disk control device 3 and the disk control device 6 via the device side bus 4.

The device-side control section 33 controls data transfer with the disk drives 51 to 53 by the disk control device 3. The backup disk 8 backs up the contents of the cache memory 62. Backup bus 7
Is a bus for connecting the disk controller 6 and the backup disk 8 to transfer data. The device-side control unit 63 controls data transfer with the disk drives 51 to 53 by the disk control device 6, and writes and reads to and from the cache memory 62 according to an instruction from the device-side control unit 33 via the device-side bus 4. Control and
The contents of the cache memory 62 are backed up by the disk 8
Write operation is controlled. The non-volatile memory 64 records backup information of the cache memory.

When there is a write instruction from the host system 1, data is written to the cache memory 32 included in the disk controller 3 via the host side bus 2 via the host side controller 31. The host-side control unit 31
The end status is returned to the host system 1 via the host side bus 2.

The disk control device 3 utilizes the time when the magnetic disk drives 51 to 53 do not perform input / output operations such as read operation, and the device side of the disk control device 6 via the drive side bus 4 connected in a daisy chain. The control unit 63 is instructed to write to the cache memory 62 and the data in the cache memory 32 is written.
Copy to.

When the contents of the cache memory 62 are changed, the device-side control section 63 uses the backup bus 7
The cache memory 6 to the backup disk 8 via
Back up the contents of 2. Backup information indicating whether the data in the cache memory 62 has been backed up is stored in the non-volatile memory 64. Even during this backup, since the input / output operation to / from the magnetic disks 51 to 53 using the disk controller 3 is not affected, the disk controller 3 can perform the normal input / output operation.

Since the data in the cache memory 32 is copied to the cache memory 62, even if a power failure occurs in the disk controller 3, the data in the cache memory 32 remains in the cache memory 62 and is not lost. When a power failure occurs in the disk controller 3 and the disk controller 6 before all the data in the cache memory 62 is backed up to the backup disk 8, the disk controller 6
When the self is restored, the host system 1 transfers the backup information stored in the non-volatile memory 64 to the host.

By referring to the backup information, the host system 1 can confirm the information of the data that has not been recorded in the disk drives 51 to 53 or the backup disk drive 8, and also when writing the data again. Since it is possible to repair by writing only the data that was desired to be recorded, the repair time can be shortened. Further, when the semiconductor disk device is used for the backup disk, the backup time can be shortened and the reliability can be further improved.

[0015]

As described above, according to the write cache backup method of the present invention, the probability that data in the cache memory is lost is greatly reduced even when a power failure occurs, and reliability is improved. It Further, even when the data is lost, the restoration time can be shortened by referring to the backup information.

[Brief description of drawings]

FIG. 1 is a system configuration block diagram of a write cache backup system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional system configuration in which a disk controller having a write-back write cache function is connected to a host system.

[Explanation of symbols]

 1 host system 2 host side bus 3 disk controller 4 device side bus 6 disk controller 7 backup bus 8 backup disk drive 31 host side controller 32 cache memory 33 device side controller 51 disk drive 52 disk drive 53 disk drive 61 Host-side control unit 62 Cash memory 63 Device-side control unit 64 Non-volatile memory

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06F 12/16 310 7623-5B G06F 12/16 310M

Claims (1)

[Claims] 1. A plurality of disk controllers having a write-back write cache function, a host-side bus for connecting each disk controller to a host system in a daisy chain, and each disk controller and a disk drive connected in a daisy chain. Device side bus for
A non-volatile memory for storing backup information of the cache memory in the connected disk control device and a disk drive for backing up the contents of the cache memory, and a backup for connecting the disk drive for backup and the disk control device. At least one disk control device having a bus is provided, and the data stored in the cache memory after the write operation from the host system is performed is transferred to the cache memory of another disk control device via the device side bus and copied. And write the copied data to the backup disk drive via the backup bus, and transfer the information that could not be backed up from the nonvolatile memory to the host system as information. Up method.