Compaq StorageWorks Data Replication Manager HSG80 ACS Version 8.5P Operations Guide

Troubleshooting 6–3
Dual Redundancy During Failback
The failback sequence is a scheduled event based upon the configuration at the failback
site. The HSG80 array controller requires that a viable dual-redundant subsystem be
available before a failback can take place. Failback to a single-controller configuration is
not supported.
Failsafe Lock Management
If failsafe mode is set for a remote copy set it can become failsafe locked if a unit fails or
the target becomes inaccessible.
If a unit fails, then the target is removed from the remote copy set. Once the unit failure
has been eliminated, the target can be re-added to the remote copy set that initiates a full
copy.
If a dual-link failure occurs, the remote copy set is placed in a failsafe locked condition.
The target remains a member of the remote copy set but is marked invalid. Once the link
has been restored to the target, a full copy is initiated. Once completed, the failsafe locked
condition is cleared.
If the initiator unit fails, the remote copy set goes into failsafe locked condition.
Link Failure Management
When an initiator controller detects that the link to its target controller is unavailable, the
initiating controller will restart. This causes all remote copy sets on the initiating
controller to failover to its dual redundant partner controller. The restart of the initiator
controller is an intended action and is not an indicator of a defective controller.
Remote Copy Set Member Failures
While most remote copy set members will be based on protected storage in the unlikely
event of a remote copy set member failure, the following operating characteristics should
be understood: