Which resynchronization method should I choose?

The manage data replication between the and the in a and is transparent to machines and applications. When the controller owner of the primary logical drive receives a write request from a host, the controller first logs information about the write to a and then writes the data to the primary logical drive. The controller then initiates a write operation to copy the affected data to the secondary logical drive on the remote, secondary .

If a link interruption or a error prevents communication with the secondary storage subsystem, the current owner of the primary logical drive changes the mirrored pair to status. The controller then sends an I/O completion to the host that sent the write request. The host can continue to issue write requests to the primary logical drive, but to the secondary logical drive do not take place.

When connectivity is restored between the controller owner of the primary logical drive and the controller owner of the secondary logical drive, takes place. Only the blocks of data that have changed on the primary logical drive during the link interruption are copied to the secondary logical drive.

Two resynchronization methods are available in the storage management software as shown in the table.

Resynchronization Method Description
(the recommended method)

The Manual Resynchronization option is the recommended method because it lets you manage the resynchronization process in a way that provides best opportunity for recovering data.

When enabled, you can manually start resynchronization of the data on the primary logical drive and the secondary logical drive after communication has been restored to the Unsynchronized mirrored pair.

When this option is selected and a communication failure occurs between the primary logical drive and the secondary logical drive, the remote logical drive mirror changes to Unsynchronized status. Any write requests to the primary logical drive are logged, and a Needs Attention status appears for the storage subsystem.

After the controller owner of the primary logical drive detects that communication has been restored, the remote logical drive mirror stays in Unsynchronized status until you select Logical Drive >> Enhanced Remote Mirroring >> Resume .

Any communication disruptions between the primary storage subsystem and the secondary storage subsystem while resynchronization is underway could result in a mix of new data and old data on the secondary logical drive. This situation renders the data unusable in a disaster recovery situation.

When enabled, automatic resynchronization starts immediately after the controller detects that communication has been restored for an Unsynchronized mirrored pair.

When the Automatic Resynchronization option is selected and a communication failure occurs between the primary storage subsystem and the secondary storage subsystem, the controller owner of the primary logical drive starts resynchronizing the primary logical drive and the secondary logical drive. This action occurs immediately after the controller owner detects that communication has been restored.