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

5–4 Compaq StorageWorks Data Replication Manager HSG80 ACS Version 8.5P Operations Guide
Failback
During Failover, the remote copy sets on the target site are in a “copy ready” state, waiting
for the initiator site to become available. When the new initiator site has been established
or the original one has been restored, site operation can resume after a failback procedure
has been performed. This involves synchronizing data on both the initiator and target
subsystems so that operation can be returned to the initiator with minimal downtime.
Verify that all components at both sites are operational before performing a failback.
The failback sequence is a scheduled event. The HSG80 Array Controller requires that a
viable dual-redundant subsystem be available before a failback can take place.
IMPORTANT: Failback to a single controller configuration is not supported.
The following table will help you understand which failback procedure to use:
Data Replication Manager Configuration Basics
The disaster-tolerant (DT) configuration that supports Data Replication Manager involves
two HSG80 array controller subsystems—one at an initiator site and one at a target site.
IMPORTANT: Because of the complexity of the configuration process, it is a good idea to have
all Data Replication Manager documentation available at both sites to eliminate confusion and
minimize the risk of error. Please follow the steps precisely in the order provided in this
documentation.
The illustration below depicts a basic DRM configuration and will be referenced
throughout this chapter.
State of the Initiator
Controller Pair
Failover
Procedure Used
Failback
Procedure
to Follow
Initiator site intact Planned Simple
Initiator site intact Unplanned Full
Initiator site not intact Unplanned New Hardware