HP 418800-B21 HP StorageWorks Replication Solutions Manager 4.0.1 user guide ( - Page 437

• No preference. Presentation of the virtual disk is completely controlled by the controller software. • Path A - Failover only. Controller A presents the virtual disk to hosts when both controllers are simultaneously started. • Path A - Failover/failback. Controller A presents the virtual disk to hosts, but if controller A fails, control of the virtual disk is transferred to controller B, then transferred back to controller A when it is available again. • Path B - Failover only. Controller B presents the virtual disk to hosts when both controllers are simultaneously started. • Path B - Failover/failback. Controller B presents the virtual disk to hosts, but if controller B fails, control of the virtual disk is transferred to controller A, then transferred back to controller B when it is available again. Presentation (to host) Presentation of a virtual disk to a host makes the virtual disk visible to the host and allows the host to perform I/O with it. After a virtual disk is presented to an enabled host, the replication manager can identify the presented virtual disk as a host volume. CAUTION: Presenting a virtual disk to more than one host at a time, or multiple times to the same host, can cause I/O write conflicts on the disk and the possible loss of host application data. Remote replication guidelines Storage arrays • Source and destination arrays must have remote replication licenses. See replication licenses overview. • The array selected for the destination DR group depends on the remote replication configuration. For supported configurations, see the HP StorageWorks Continuous Access EVA planning guide. • A storage array can have DR group relationships with up to two other storage arrays. • The maximum number of virtual disks in a DR group and the maximum number of DR groups per array vary with controller software versions. See controller software features - remote replication. DR groups and failover • Failover of a DR group pair is permitted only by specifying a destination DR group. • When failsafe on unavailable member is enabled, a DR group pair cannot be suspended. See failsafe on unavailable member, suspend on failover. • When a DR group pair is suspended, it cannot be failed over or reverted to home. • A DR group cannot be deleted if a virtual disk in the destination DR group is presented. • For additional help on usage, see using DR groups. Virtual disks • All virtual disks that contain the data for an application must be in the same DR group. • When in enhanced asynchronous write mode, virtual disks cannot be added to or deleted from a DR group. This restriction is controller software version dependent. See controller software features - remote replication • When suspended, virtual disks cannot be removed from the source or destination DR group. • Virtual disks cannot be directly added to a destination DR group. • To be added to a source DR group, a virtual disk: • Cannot be a member of another DR group HP StorageWorks Replication Solutions Manager 4.0.1 437