Software Manual

4.4
Setting Remote Copy Volume Group Policies
Remote Copy User’s Guide InForm OS Version 2.3.1
4.4 Setting Remote Copy Volume Group Policies
In addition to switching the target for a volume group, the setrcopygroup command can
also be used to set Remote Copy policies for volume groups.
There are four policies that can be applied to volume groups. The
fail_wrt_on_err and
no_fail_wrt_on_err policies apply to synchronous Remote Copy only.
■ fail_wrt_on_err The fail_wrt_on_err group policy ensures that the two copies are
always in synchronization by refusing to write changes to a volume group on one server
when the links between the members of the Remote Copy pair are broken for any reason.
This prevents the primary and secondary volume groups from becoming out of
synchronization with each other.
This policy can be set for disaster recovery applications where the Remote Copy must be up-
to-date at all times and where an application outage for a brief period can be tolerated
(for example if the links or one member of the Remote Copy pair fails).
■ no_fail_wrt_on_err (default policy) The no_fail_wrt_on_err group policy allows
writes to a primary volume group even though the link between the systems in the Remote
Copy pair is broken. Continuing to write changes despite a broken link leads to a loss of
synchronization between primary and secondary volume groups.
The
no_fail_wrt_on_err policy is used when you would rather keep the applications
that are writing the data running, even when the Remote Copy has failed and become out
of sync. After the error that caused the broken link is resolved, you must manually restart
the Remote Copy operation between the members of the Remote Copy pair to bring the
Remote Copy in sync again.
CAUTION: There is no default synchronization period. Therefore, if you do not
specify a synchronization period using the
setrcopygroup command, automatic
resynchronizations will not take place.
NOTE: When you set group policies for a primary volume group using
setrcopygroup, this command is automatically mirrored to the secondary
volume group.