HP P6000 Replication Solutions Manager User Guide (T3680-96089, October 2012)

3. Suspension state1. Operational state
4. Log state2. Failsafe state
Failover
To fail over means to reverse the direction of remote replication in a DR group pair. A failover
event is an event in which the remote replication direction was reversed.
When a failover event occurs, the roles of source and destination in a DR group pair are reversed.
For example, in a planned failover, if DR group A was originally the source and DR group B was
the destination, those roles are reversed when DR group B is failed over.
In the case of an unplanned failover (disaster), there may not be a literal reversal of remote
replication because Site A might not be operational. Instead, when DR group B is failed over, Site
B can become an independent site, or a source that remotely replicates to third site.
Performing a planned or unplanned failover involves technical preparation and significant
operational planning. Host I/O is impacted by a failover. The following guidelines capture just a
few of the technical considerations.
• To fail over a DR group pair, you must specify the destination DR group. See DR group pair.
• You cannot fail over a DR group pair if remote replication is suspended or if a remote copy
(virtual disk) is in an unknown state. See DR groups Suspension state and virtual disks Resource
states.
• You can failover a DR group while it is normalizing.
• If only one component in a DR group pair fails, repairing that single component may be
preferable to performing a failover.
IMPORTANT: Failing over a DR group pair impacts host I/O. Ensure that you understand
the potential impacts of performing a failover. For more information on failover, see the HP
P6000 Continuous Access Implementation Guide.
See also DR groups Suspend on failover and Remote replication guidelines.
Failsafe on link-down/power-up
Failsafe on link-down/power-up is a data protection feature that specifies whether or not virtual
disks in a source DR group are automatically re-presented to hosts after a power-up (reboot) of the
source storage system when the links to the destination DR group are down. Values are:
• Enabled. When enabled, virtual disks in a source DR group are not automatically re-presented
to hosts after a link-down/power-up (reboot) of the source storage system. This behavior is
called presentation blocking and provides data protection under several circumstances. See
Operational State - Blocked.
• Disabled. When disabled, virtual disks in a source DR group are automatically re-presented
to hosts after a link-down/power-up (reboot) of the source storage system.
82 DR groups