11.1.1 How disaster recovery works

(1) Begin operation on main site and copying between shared disks

After building the disaster recovery environment, begin operation on the main site and initiate the process of copying data between the main and remote sites.

The JP1/AJS3 services on the logical host (for disaster recovery operation) at the remote site do not start running while the JP1/AJS3 system is still operating at the main site.

Figure 11‒2: Initiating operation at main site and copying between shared disks

Supplementary note

Because the logical host prepared for disaster recovery at the remote site does not run any JP1/AJS3 services while the JP1/AJS3 system is operating at the main site, you cannot connect to the logical host at the remote site using JP1/AJS3 - View, or other products.

To Page Top

(2) A major event causes the main site to go down

If the system at the main site stops running due to a large-scale disaster or other event, use a hardware operation at the remote site to stop the copy process between shared disks. Then, change the status of the remote volume to write-enabled.

Figure 11‒3: The main site goes down in the event of a large-scale disaster

To Page Top

(3) Switch operation to the remote site

Operation switches to the main site, from which point the logical host on the remote site becomes the active site. Suppression of the JP1/AJS3 services on the remote site is then released, a disaster recovery restart is performed for the JP1/AJS3 services on the remote site, and work task operation resumes.

Figure 11‒4: Switching operation to remote site

To Page Top

(4) Rebuild the main site

Rebuild the JP1/AJS3 system on the disaster-affected main site. When this is done, begin copying data from the remote site back to the main site.

Figure 11‒5: Rebuilding the main site

Supplementary note

Until the system is recovered on the main site, use the standard JP1/AJS3 backup process to take backups of the system on the remote site.

To Page Top

(5) Return operation to the main site

Stop the JP1/AJS3 services at the remote site, and make sure that no jobs are running. Having done so, stop the process of copying data from the remote site to the main site. Next, use a hardware operation to change the status of the main volume to write-enabled, and then switch operation so that the logical host on the main site becomes the active site. (This action is referred to as returning operation.) When this process is completed, the hold placed on the JP1/AJS3 services on the main site is released, and a hold is instead placed on the JP1/AJS3 services on the remote site. A remote copy process is initiated from the main site to the remote site, the JP1/AJS3 services are started on the main site, and work task operation is resumed. The first time that the JP1/AJS3 services start after returning operation, the services are subject to a disaster recovery start.

Figure 11‒6: Returning operation to the main site

To Page Top