JPS648848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data backup method for a magnetic disk device, magnetic drum device, etc. in an electronic computer system. For convenience, a magnetic disk device will be described below, but the same applies to a magnetic drum device.

Data on the magnetic disk device is subject to changes as jobs are executed by the computer system.
On the other hand, in a magnetic disk device, stored data may be lost due to a failure of the magnetic surface. For this reason, generally after all jobs are completed,
A method is used in which data on a magnetic disk device is copied to another storage medium such as a magnetic tape. but,
Conventionally, the method of copying the entire area of data on a magnetic disk device or the entire area of data assigned to a data set has been used, which has caused the problem that it takes too much time to back up the data.

An object of the present invention is to eliminate the above-mentioned conventional problems, and to provide a method for backing up data on a magnetic disk device, etc., which has the effect of shortening the time required for backing up. be.

A feature of the present invention is that in an external storage device such as a magnetic disk device in a computer system, a memory that records the location of data that has been changed due to the execution of a job is stored in the external storage device such as a magnetic disk device. The time required for backup can be reduced by preparing the data beforehand and copying only the changed data to another external storage device such as a magnetic tape.

Hereinafter, the content of the present invention will be explained in detail with reference to illustrated embodiments.

Figure 1 shows the overall configuration of the electronic computer system.
1 is the central processing unit (CPU), 2 is the main memory (MM), 3 is the input/output processing unit (IOP), 4 is the data channel (CH), and 5 is the disk controller connected to one CH ( DKC), 6 is an external storage device of a magnetic disk device (DK) under the control of DKC. When the central processing unit 1 issues an input/output command to the input/output processing unit 3 in accordance with the execution of a certain job, the input/output processing unit 3 issues the magnetic disk unit 6 via the data channel 4 and the disk control unit 5. It is activated, and thereafter data transfer between the main storage device 2 and the magnetic disk device 6 is executed independently of the processing of the central processing unit 1. Although not shown in Figure 1, another external storage device for the magnetic tape device is connected to another data channel, and when all jobs are completed, the data on the magnetic disk device is copied to the magnetic tape device. be done. At this time, the present invention copies only the changed data to the magnetic tape device.

FIG. 2 is a block diagram of a magnetic disk device, in which 7 is a control section, 8 is a magnetic disk body, and 9 is a control memory. Here, a control memory 9 is added according to the present invention. The control memory 9 has one address with one bit, and each address has a one-to-one correspondence with all tracks of the magnetic disk body 8. For example, 0 of control memory 9
The address indicates the 0 track of the magnetic disk 8, and hereinafter, the 1 address, . . . indicate the 1 track, 2 track, . . . , respectively, and the i address generally corresponds to the i track. When an output command to the magnetic disk device is issued, the control unit 7 sets the corresponding address in the control memory 9 corresponding to the track to which the data is output to indicate that the output has occurred, that is, logic "1". . After all the jobs have been executed, the central processing unit 1 stores the control memory 9 in accordance with a program (copy program).
The content is read out, and only those tracks for which there is an indication that an output has been made (that a change has been made) are copied onto another recording medium such as a magnetic tape.

FIG. 3 is a diagram illustrating a data backup method according to the present invention, and a more detailed explanation will be given below based on this.

First, the central processing unit 1 executes a copy program to copy all tracks on the magnetic disk 8.
Copy data to magnetic tape. This is an expired copy; the data is stored on the magnetic tape unless changed by a job. Thereafter, the central processing unit 1 instructs the magnetic disk device 6 to reset the contents of the control memory 9, and the control unit 7
The control memory 9 is then reset. Figure 3A
shows this state. Next, the central processing unit 1 executes the job, and when an output command is issued to the magnetic disk device 6, the control unit 7 writes data into the corresponding track on the magnetic disk 8 for which the command was given, and also writes the data into the control memory 9. Set "1" to the corresponding address above. FIG. 3B shows this state.

After all jobs have been executed, the central processing unit 1 reads the contents of the control memory 9 in the magnetic disk device 6 using the copy program. Then, it is determined which track on the magnetic disk 8 has been changed based on the contents of the control memory 9, and a command is sent to the input/output processing unit 3 to copy the contents of the changed track on the magnetic disk 8 to the magnetic tape. Issued to.
When the input/output processing unit 3 completes the predetermined copying process, the control unit 7 of the magnetic disk device 6 is activated in accordance with the instructions from the central processing unit 1, similar to the case shown in FIG. 3A.
resets the contents of control memory 9. Figure 3C
indicates this state.

If the magnetic disk is destroyed due to a magnetic surface failure, etc., as shown in Figure 3D, a copy of the magnetic tape covering the entire magnetic disk made by the process in Figure 3A and the modified magnetic tape made in Figure 3C can be used. Creates the latest data on the magnetic disk using the area's magnetic tape as input,
Restore to magnetic disk device.

In the embodiment shown in FIG. 2, the control memory 9 is addressed in a one-to-one correspondence with each track of the magnetic disk 8, but the addressing of the control memory 9 is based on the location of the changed data. There is no need for a one-to-one relationship with each track as long as the

With the configuration as described above, the following effects can be obtained with the present invention.

(1) Tracks on which data has been changed, such as on a magnetic disk device, are recorded in hardware, and after a series of jobs has been executed, only the changed tracks are copied all at once using a program. , the time required for backing up magnetic disk devices, etc. is reduced.

(2) Since the amount of data to be copied is smaller than in the past, the amount of separate storage media required for backup can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a computer system, FIG. 2 is a schematic configuration diagram of a magnetic disk device, and FIG. 3 is an explanatory diagram of the system of the present invention. 1...Central processing unit, 2...Main storage device, 3...
...I/O processing unit, 4...Data channel, 5
...Magnetic disk control device, 6...Magnetic disk device, 7...Control unit, 8...Magnetic disk main body,
9...Control memory.

Claims (1)

[Claims] 1. Data in an external storage device such as a magnetic disk device or magnetic drum device (hereinafter referred to as the first external storage device) shall be stored in another storage device such as a magnetic tape device as backup data in the event of a failure, etc. after the execution of a job is completed. External storage device (hereinafter referred to as the second external storage device)
In the data backup method for copying data to a series of jobs, a control memory is installed in the first external storage device to record the location of data on the first external storage device that has been changed by executing a job. After the execution of the control memory is completed, the content of the control memory is read out, and based on the content, only the changed data on the first external storage device is copied to the second external storage device. method.