HP StorageWorks Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide (AA-RPHZF-TE, March 2004)

Remote Copy Set Features
42 Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide
ORDER_ALL Switch
When the ORDER_ALL switch of the ADD ASSOCIATIONS command is enabled, the order
of all asynchronous write operations across all members of the association set is preserved. No
write history log unit is required.
With the ORDER_ALL switch enabled and write history logging enabled, if one member of the
association set starts write history logging, all members of the association set start write
history logging. This allows the mini-merge to replay the writes in the same order received
from the host.
If NOORDER_ALL is enabled, the members of the association set can start and finish write
history independently. NOORDER_ALL is the default setting.
SUSPEND
The SUSPEND switch of the SET remote-copy-set-name CLI command allows
suspension of write operations to the target so that the target can be used for backup. This
switch starts the write history log process for the specified target.
This command is issued at the initiator site, even though the backup is occurring at the target
site.
RESUME
The RESUME switch of the SET remote-copy-set-name CLI command allows
resumption of write operations to the target. The SUSPEND command must previously have
been entered for this command to be valid.
This command starts the mini-merge process for restoration of the specified remote target unit.
Failover
There are two types of failover:
■ Planned failover (due to a planned takedown of one of the systems, to perform
maintenance, for example)
■ Unplanned failover (due to a failure within the DRM system)
For more detail on failover and failback, refer to the HP StorageWorks Data Replication
Manager HSG80 Version 8.7P Failover/Failback Procedures Guide.
Planned Failover
A planned failover allows for an orderly shutdown of controllers. The host applications are
quiesced and all write operations are permitted to complete before shutting down the
controllers, so that no data is lost or jeopardized. A planned failover requires a synchronous
operation mode.
Note: To implement a planned failover while in asynchronous operation mode, you must first
switch to synchronous operation.