JPH05241971A - Restoring method for data on memory - Google Patents

Abstract

PURPOSE:To improve area efficiency for an external memory device required for the restoration of data on memory. CONSTITUTION:The data (a), (e) to which update is applied out of the data on the memory are outputted to the external memory device as update information simultaneously with the update. The update status of the data on the memory is checked at each lapse of constant time after a system is started up, and the information of (b), (c), (d), (f),..., (z) on which no update is performed are outputted. The restoration of the data on the memory is performed by reading in the data sequentially from a position tracing back for a time (t) from outputted last data, and loading it on the memory, which enables the data on the memory to be restored. A file is read in when the system is started up first, and the data is developed on the memory. Hereinafter, the processing of an on-line system, etc., can be performed only by updating the data on the memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering data on a memory.

[0002]

2. Description of the Related Art Conventionally, the data on the memory is restored by creating the same file as the data on the memory in an external storage device.
The file is made resident in the memory for processing, or a plurality of original files are read and the data is expanded in the memory.

[0003]

Among the conventional methods for recovering data on memory, the method of creating the same file as the data on memory uses two files, the same file as the memory data and the original file. Data will be managed, and the area efficiency of the external storage device will decrease.
There is a problem that the processing time for updating the file is reduced.

Further, in the method of reading all the original files without creating the same file as the data on the memory, the file is different depending on the data to be updated. There was a problem that time was reduced.

[0005]

According to the method of restoring data in memory of the present invention, the data expanded in the memory is updated each time it is updated, and at regular intervals after system startup, during that period. If it is not updated, it is output to the external storage device after the elapse of the predetermined time, and at the time of data recovery, the data output to the external storage device is read from the predetermined time before and loaded into the memory. Is characterized by.

[0006]

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

In FIG. 1, when the data a and e on the memory are updated by the program, the updated flag is set to "1", and the data a and e are output to the external storage device.

Next, when a certain time t has elapsed from the time when the system was started up, "0" data b, c, d, f, g, h, i which has not been updated is checked by looking at the update flag of the data on the memory.
...... Outputs z on the external storage device. Furthermore, if the data a and e are not updated during the elapse of the fixed time t,
Since the update flag changes from "1" to "0", the data a, et external storage device is output 2t after the system is started. Thus, the data update flag of "0" on the memory is output to the external storage device every time t has elapsed.

When it is necessary to restore the data to the memory when the system is started up or when the system is restarted after the system goes down, the time is traced back from the latest output position of the external storage device outputting the information by t hours. The data is sequentially read from the position, and the output data is loaded on the memory to restore the data on the memory.

[0010]

As described above, the restoration of the data on the memory outputs the updated data to the external storage device at the same time, and the data that has not been updated remains constant for a certain period from the system startup. It is output to the external storage device in a cycle, and when the data is restored, by sequentially reading the data from a position that is a certain time back from the latest position of the information output to the external output device and loading it on the memory,
All data can be restored. As a result, it is possible to read a file when the system is first started up and expand the data in the memory, and thereafter to perform the processing of the online system or the like simply by updating the data in the memory.

[Brief description of drawings]

FIG. 1 is a diagram showing how update data is output in the present invention.

FIG. 2 is a diagram showing how data that has not been updated for a certain period of time is output in the present invention.

FIG. 3 is a recovery diagram of memory data.

[Explanation of symbols]

a, b, c, ..., z Identification code of data division unit on memory A, B, C, D Data contents

Claims (1)

[Claims] 1. The data expanded on the memory,
It is output to the external storage device each time when it is updated, and at a fixed time after system startup, and during the fixed time when it is not updated during that time, and is output to the external storage device when data is restored. A method for recovering data in a memory, characterized in that the data is read from a certain time before and loaded into the memory.