Hp LeftHand P4000 Virtual SAN Appliance Software User Manual download pdf (Page 34)

Failover to the backup application server

To maintain availability of the applications and the remaining data, the following process occurs:

1. A script or other application monitoring the production application server discovers that the

primary volume is not available. A script executes to fail over to the backup application server.

2. The backup application server executes a script to convert the remote volume into a primary

volume so that the volume can be accessed by the backup application server. For information

about scripting, see the CLIQ—The SAN/iQ Command-Line Interface User Manual and the

sample scripts available at http://www.hp.com/go/P4000downloads.

3. Because the backup application server was configured to access the remote (now primary)

volume, operation of the backup application server begins.

The application continues to operate after the failover to the backup application server.

Failback to the production configuration

When the production server and volumes become available again, you have the following two

failback options:

• Resume operations using the original production server, and then return the backup volumes

to their original remote status, as illustrated in “High availability configuration during failback”

(page 34). This requires migration of data that was written to the backup volumes since the

failure back onto the production volumes.

• Continue operating on the backup application server. When the production server and volumes

become available, configure the production server to be the backup server (role reversal).

Merging data for failback

In the failover scenarios described above, there are probably two snapshots with different data.

As part of failback, users must make a decision whether to merge the data from the two snapshots

and the most effective method for doing so. For more information see “Synchronizing the data

between the acting primary volume and the original primary volume” (page 28).

Figure 12 High availability configuration during failback

34 Sample Remote Copy configurations

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Hp LeftHand P4000 Virtual SAN Appliance Software User Manual Page 34