JPH0553732A - Dual disk system - Google Patents

Abstract

PURPOSE:To increase the processing speed and to shorten the starting time for operation of a duel disk in a dual disk system by making use of the characteristics of a semiconductor disk and a magnetic disk. CONSTITUTION:A semiconductor disk 6 can write and read the data at a speed higher then a magnetic disk a and also can hold the data with back-up of a battery 7 even with e power failure defined within a specified time. The disk a has the same capacity as the disk 6 and prepares for a case where the data stored in the disk 6 are erased due to a power failure longer than the specified time. A duplex processing part 9 transfers the data between both disks 6 and 8 based on a program. A disk cache processing part 10 stores the data in a disk cache memory 12 and also writes the data in the disk 8. A recovery processing part 11 recovers a duel disk system based on the contents of a recovery map memory 13. Thus the operation of the system is started with the newly exchanged device used as a follower device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual disk system in a computer system.

[0002]

2. Description of the Related Art In a computer system, data to be stored is usually written on a magnetic disk. In consideration of the case where these data become illegal, a dual disk in which two disk devices of the same capacity are prepared and double-written is used in a system that places importance on data preservation.

FIG. 2 shows a conventional dual disk system of this type. In FIG. 2, 1 is a general program section, 2 is a duplicated program section, 3a is a first magnetic disk which is a main disk, and 3b. Is a second magnetic disk which is a slave disk. Arrows 4a to 4c show the flow of write data to the disk device, and arrows 5a and 5b show the flow of read data from the disk device when the first magnetic disk 3a is "main".

In the dual disk system of FIG. 2, the general program issues the same "write" and "read" requests to the duplicated program as to the single disk device. The duplication program has the following functions.

(1) The two main magnetic disk devices are recognized as "main" and "subordinate". (2) A "write" request is made to the "main" and "subordinate" magnetic disks, but a "read" request is made from the "main" magnetic disk. (3)
When illegal data is detected in the "writing" or "reading" of the "main" disk, the other healthy disk is newly operated as the "main". (4) When a serious error occurs in the "main" or "subordinate" disk, disconnect the device and operate as a single disk device.

[0006]

In the conventional dual disk system, when viewed from a general program,
The time required for "writing" and "reading" was slower than that of a single disk device. The cause is due to the delay due to the existence of the duplication program and the delay due to "writing" to the two disk devices.

Further, when one magnetic disk device becomes abnormal and is replaced with a spare device, all data must be copied from another healthy disk device to the spare disk device. It took time to resume operation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a dual disk system capable of speeding up the processing and shortening the operation start time of the dual disk.

[0009]

In order to achieve the above object, the present invention provides a dual disk system including a semiconductor disk with a battery backup, magnetic disks arranged in parallel with the semiconductor disk, and these semiconductor disks. A duplication processing unit that sends and receives data according to a program set for a magnetic disk, a disk cache processing unit that writes data to the magnetic disk, and stores data from this disk cache processing unit. A disk cache memory for inputting to the magnetic disk, a recovery map memory for performing recovery processing when the semiconductor disk or the magnetic disk is abnormal, and a recovery processing unit.

[0010]

According to the program, the duplication processing section exchanges data with the semiconductor disk and the magnetic disk,
The disk cache processing unit stores the data in the disk cache memory and writes the data in the magnetic disk. The recovery processing unit recovers the system according to the contents of the recovery map memory.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 6 is a semiconductor disk which is a main disk, 7 is a battery which is a backup power source,
Reference numeral 8 is a magnetic disk which is a slave disk, 9 is a duplication processing unit, 10 is a disk cache processing unit, 11 is a recovery processing unit, 12 is a disk cache memory, and 13 is a recovery map memory.

In the system of FIG. 1, the semiconductor disk 6 is much faster than the magnetic disk 8 in “writing”.
A "read" process is possible. Further, the backup by the battery 7 enables the data to be retained even during a power failure within a specific time. The magnetic disk 8 is a normal disk device, has the same capacity as the semiconductor disk 6, and is provided in case the data of the semiconductor disk 6 is lost due to a power failure for a specific time or longer.

The duplication processing section 9 has a function equivalent to that of the duplication program. The disk cache memory 12 and the disk cache processing unit 10 correspond to the magnetic disk 8 and complete the request for the “write” request when the requested data is written in the disk cache memory 12. In the idle time thereafter, the write request data on the disk cache memory 12 is transferred to the magnetic data 8 as background processing.
Write to. Only when the disk cache memory 12 is empty when the "write" request is made, the magnetic disk 8 is directly used.
Go to write to.

When the magnetic disk device 8 becomes the "main" and a "read" request is received, the disk cache memory 12
If the relevant data exists above, that data is transferred. If it does not exist, the corresponding data is read to the magnetic disk 8. In this way, the "write" and "read" requests for the magnetic data 8 are speeded up.

The recovery map memory 13 and the recovery processor 11 function when the semiconductor disk 6 or the magnetic disk 8 becomes abnormal and is replaced with a spare device.

In the conventional dual disk, the operation as a duplicated disk was restarted after copying all the data from the sound disk to the spare device that was replaced, but in the system of the present invention, it is newly added after the device replacement. The device installed at will immediately start operating as a "servant".

After that, the following processing is executed.

(A) All flags in the recovery map memory are set to "0". (B) Every time data is written to the "slave" disk device by the "write" request, the flag of the recovery map memory corresponding to the written data area is set to "1". (C) Copying the data corresponding to the flag that remains "0" on the recovery map memory from the "main" disk device to the "slave" disk device in the idle time of the process for the disk device (as background processing). .. Then, the corresponding flag is set to "1". This process is repeated as the background process until the "0" state flag disappears.

[0020]

Although the processing speed of the semiconductor disk is much faster than that of the magnetic disk, it is impossible to store the data for a long time, so that the data can be temporarily used (the data does not need to be stored for a long time). It has only been used for. In the present invention, by adopting "battery backup" and "duplication with magnetic disk", while utilizing the high speed processing which is an advantage of the semiconductor disk device, it is possible to store data which is a disadvantage for a long period of time. .. In addition, by adopting the disk cache processing method for magnetic disks, "writing" is possible compared to the case of using only magnetic disks.
The "read" request is completed in a short time. Although it depends on the capacity of the disk cache memory, it is particularly effective when a small amount of data is frequently written at random time intervals. Therefore, the "write" and "read" times can be shortened.

Further, in the conventional system, when the disk device is replaced, the operation as a duplicated disk cannot be resumed until after copying all the data to the newly installed device, and during this period, a considerable waiting time is required. It took time. In the present invention, this waiting time is completely unnecessary, and it becomes possible to operate as a duplicated disk immediately after a new device is installed.
In data recovery to a new device, the "write" request is usually prioritized, and other data is copied as background processing, so the recovery processing has little effect on the general write request. Therefore, 2 after the disk device replacement
The start-up time of the duplicated disk can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of a dual disk system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional dual disk system.

[Explanation of symbols]

1. General program section, 4a to 4c ... Flow of write data to disk device, 5a, 5b ... Flow of read data from disk device, 6 ... Semiconductor disk, 7 ... Backup battery, 8 ... Magnetic disk, 9 ... Duplication processing unit, 1
0 ... Disk cache processing unit, 11 ... Recovery processing unit, 12 ... Disk cache memory, 13 ... Recovery map memory.

Claims (1)

[Claims] 1. A semiconductor disk with a battery backup, a magnetic disk arranged in parallel with this semiconductor disk, and a duplication processing unit for exchanging data according to a program set for these semiconductor disk and magnetic disk. A disk cache processing unit that writes data to the magnetic disk, a disk cache memory that stores data from the disk cache processing unit and inputs the data to the magnetic disk, and an abnormality of the semiconductor disk or the magnetic disk. A dual disk system characterized by a recovery map memory for performing recovery processing and a recovery processing section at times.