Dell EqualLogic PS6210XS EqualLogic Group Manager Administrator s Guide PS Ser - Page 302

• Disconnect the SyncActive volume, as documented in the Group Manager online help. If the disconnect fails, try logging in to a different member in the SyncActive pool. NOTE: If the disconnect operation will not succeed from any member in the SyncActive pool, contact your Dell support provider for assistance. • Log in to the Group Manager GUI using an IP address that belongs to a group member in the pool containing the SyncAlternate volume. Do not use the group IP address. • Fail over the volume. 5. Set the volume back online, restoring initiator access. The new SyncActive volume (formerly SyncAlternate) accepts writes and tracks changes made while the original SyncActive volume is offline. Depending on host configuration and application requirements, you might have to restart hosts that were connected to the volume. 6. After access to the volume has been restored, the system performs the following steps: a. When the original SyncActive volume is available again, it becomes the SyncAlternate volume. b. Synchronous replication resumes. The volume is out of sync, and tracked changes are written to the new SyncAlternate volume. c. When the volume becomes in sync again, new writes are simultaneously written to both pools. You can switch back to the original pool configuration, or continue using the new pool configuration. Requirements for Using Synchronous Replication Before you can configure a volume to use synchronous replication, verify that the following requirements are met: • Two pools, each containing at least one member • Adequate network bandwidth between pools • Free space in each pool to accommodate the volume and snapshot reserve for the volume Also note the following restrictions: • You cannot enable synchronous replication on a volume for which traditional replication is configured, and you cannot enable traditional replication on a volume for which synchronous replication is configured. • You cannot enable synchronous replication on a volume that is bound to a group member. See About Overriding Automatic Load Balancing for more information about binding and unbinding volumes. • To support up to 32 volumes for synchronous replication, a PS Series group must contain only PS6cxx0 arrays. If the group contains one or more PS4xx0 arrays, only 4 volumes are supported. Synchronous Replication States Synchronous replication states for a volume include: • in sync SyncActive and SyncAlternate copies of a volume contain the same data. • paused Administrator has paused synchronous replication. While synchronous replication is paused, the volume is still online, and initiators can connect to and write to the SyncActive volume. An administrator might pause and later resume synchronous replication. For example, this situation could happen in a maintenance window during which the SyncAlternate volume is taken offline. If data is written to the volume while synchronous replication is paused, it is written only to the SyncActive volume, and the two volumes are out of sync. The group tracks all volume writes while synchronous replication is paused and, when the administrator resumes synchronous replication, writes the tracked changes to the SyncAlternate volume. • out of sync SyncActive volume and SyncAlternate volume might not contain the same data; the SyncActive volume contains the most recent data. 302 About Synchronous Replication