JPH07141240A - Fault recovery system for doubled media - Google Patents

Abstract

PURPOSE:To start the use as the doubled media again by copying all the data on one medium from the other medium after a recovery from a fault of the other medium without stopping the operation of application software. CONSTITUTION:For example, when an external medium 1 is incorporated in a system after the fault recovery, a control part 3 copies the data from an external medium 2 to the external medium 1 in order. If a request for writing to the external medium is made by the application software during the copying operation between the media, the control part 3 interrupts the copying operation between the media, and passes the control to a control part 4 after recording the address (interruption address) of data which is copied finally at a monitor part 5. The control part 4, after writing the contents requested to be written on the media 1 and 2, returns the control to the control part 3. The control part 3 refers to the interruption address recorded at the monitor part 5 and then restarts the copying operation between the media at the next address.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a system in which an external medium is duplicated, if one medium fails, this medium is separated, and only the other medium in which no failure has occurred is used. The present invention relates to a duplex medium failure recovery method that enables all data to be copied from the other medium to the one medium after the failure recovery of the medium and restarts the operation as the duplex medium.

[0002]

2. Description of the Related Art Conventionally, in this type of system, an external medium is duplicated, and when one medium fails, this medium is disconnected, and only the other medium which has not failed, that is, a normal medium. It is being operated in. Here, after the failure of one medium is recovered, the other medium (normal medium) is replaced with the other medium (medium in which the failure is recovered).
By copying all the data to, the operation as a duplicated medium can be resumed. Therefore, conventionally, the business operation of the application is stopped, and the medium-to-medium copy from the other medium to the one medium is performed in a state where there is no new / update writing of the data content.

[0003]

However, according to such a conventional failure recovery method, there is a problem that the business operation of the application must be stopped while the medium-to-medium copy is being performed.

The present invention has been made in order to solve such a problem, and an object of the present invention is to recover one of the media from the other media after the failure recovery of the one media without stopping the business operation of the application. It is an object of the present invention to provide a failure recovery method for a duplicated medium that can copy all data to the medium and resume operation as a duplicated medium.

[0005]

In order to achieve such an object, according to the present invention, after the failure recovery of one medium, data is sequentially copied from the other medium to the one medium, If there is a request to write to an external medium during copying, record how far the medium-to-medium copy was executed, write the requested content to one or the other medium, and then restart the medium-to-medium copy. It was done like this.

[0006]

According to the present invention, therefore, if there is a write request to an external medium during inter-medium copying, the contents requested by the write are written to one and the other medium. Then, after the end of writing the contents of the write request to both media, the inter-media copy is restarted.

[0007]

EXAMPLES The present invention will now be described in detail based on examples. FIG. 1 is a block diagram showing a main part of a system to which the present invention is applied. In the figure, 1 and 2 are external media, 3 is a control unit for controlling inter-media copying between the external media 1 and 2, and 4 is a normal read / write control for the external media 1 and 2. The control unit 5 is a monitoring unit that records how much the medium-to-medium copy has been executed.

Next, a peculiar operation in this system will be described together with the functions of the respective parts. Now, after a failure occurs in the external medium 1 and only the external medium 2 is used,
It is assumed that the external medium 1 is incorporated in the system after the failure recovery. When the external medium 1 whose fault has been restored is installed in the system, the application issues an inter-media copy request to the control unit 3.

The control unit 3 sequentially copies data from the external medium 2 to the external medium 1. When there is a write request from the application to the external medium during this inter-medium copy, the control unit 3 interrupts the inter-medium copy, notifies the monitoring unit 5 of the address of the last copied data, and then sends it to the control unit 4. Pass control The monitoring unit 5 records the address notified by the control unit 3 as an interruption address. The control unit 4 writes the content of the write request to the external media 1 and 2, and returns the control to the control unit 3 after the writing to both media is completed.

The control unit 3 refers to the interruption address recorded in the monitoring unit 5, and restarts the medium-to-medium copy from the address next to the interruption address. When the medium-to-medium copy up to the last address is completed in this way, the external medium 1 and the external medium 2 have the same data content, and the operation as a duplicated medium can be resumed.

[0011]

As is apparent from the above description, according to the present invention, after the failure recovery of one medium, the data is sequentially copied from the other medium to the one medium, and during this inter-medium copying. If there is a request to write to an external medium, it records how far the medium-to-medium copy was executed, writes the requested content to one or the other medium, and then restarts the medium-to-medium copy. So
After the failure recovery of one medium, all data can be copied from the other medium to the one medium and the operation as a duplicated medium can be resumed without stopping the business operation of the application.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a system to which the present invention is applied.

[Explanation of symbols]

 1 External Medium 2 External Medium 3 Control Unit 4 Control Unit 5 Monitoring Unit

Claims (2)

[Claims] 1. A system in which an external medium is duplicated, and when one medium fails, this medium is separated and only the other medium in which no failure has occurred is used , Data is sequentially copied from the other medium to the one medium, and if there is a write request to the external medium during this inter-medium copy, the extent to which the inter-medium copy is executed is recorded and then the writing is performed. A failure recovery system for a duplicated medium, characterized in that after the requested contents are written to the one and the other medium, inter-media copying is restarted. 2. In a system in which an external medium is duplicated, and when one medium fails, this medium is separated and only the other medium in which no failure has occurred is used Data is sequentially copied from the other medium to the one medium, and if there is a write request to an external medium during this medium-to- medium copy, the medium-to-medium copy is interrupted and the address of the last copied data is set. While recording, the contents requested to be written are written to the one and the other medium, and then the inter-medium copy is restarted from the address next to the recorded address. Disaster recovery method.