Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF

4. After the resynchronization is completed, enable the package switching on the node on R2
side.
# cmmodpkg -e pkgname -n node_name
5. Re-establish the BCV to R2 devices on R2 as a mirror.
# symmir -g dgname -full est
Alternatively, from the node on R1 side.
# symmir -g dgname -full est -rdf
In Metrocluster with EMC SRDF environment, following the resynchronization process described
above, which prevents the package from automatically failing over and starting on the R2 side if
a disaster takes place when the resync is in progress. This ensures the package would not
automatically start and operate on the inconsistent data in the event of a rolling disaster.
As demonstrated above, the re-sync is a manual process and initiated by an operator after the
links are fixed. The pairstate of the devices must be Synchronized for SRDF/Synchronous or
Consistent for SRDF/Asynchronous when the re-sync is completed. Verify the state and ensure that
the re-sync is completed before enabling the package switch.
R1/R2 swapping
This section describes how the R1/R2 swapping can be done via the Metrocluster package and
manual procedures. Each of these methods allow swapping the SRDF personality for each device
designation of a specified device group. In this situation, every source R2 device becomes a target
R2 device, and a target R1 device becomes a source R1 device.
R1/R2 swapping using Metrocluster with EMC SRDF
The Metrocluster SRDF package can be configured to automatically carry out the R1/R2 swapping
upon package failover. To enable R1/R2 swapping in the package, set the modular package
parameter AUTOSWAPR2 in the package configuration file to 1 or 2. Because the swap is
done automatically upon package start up, the Metrocluster SRDF software performs the swap if
the Symmetrix frames and the SRDF links between them are working properly, that is, the SRDF
state of the device group is in Synchronized state. If the failover and swap operations succeed,
then the devices personalities are switched, and the data replication continues from the new R1
devices to the new R2 devices.
Before Metrocluster performing an R1/R2 swap, if the failover operation fails, the package is not
automatically started. If the failover operation succeeds, but R1/R2 swapping fails, then either the
package automatically starts, or fails depending on the value of the environment variable
AUTOSWAPR2.
You can set the environment variable AUTOSWAPR2 to either “1” or “2”. This depends on whether
the package must be automatically started on R2, in case of R1/R2 swap failure.
If AUTOSWAPR2 is set to “1”, the package fails to start when R1/R2 swapping fails. In such a
scenario it is necessary to manually start the package by performing the swap operation. If preferred,
this can be done at a later time.
If AUTOSWAPR2 is set to “2”, the package is automatically started regardless of an R1/R2 swap
failure. In such a scenario the data is not protected remotely.
NOTE: When failing over a package with R1/R2 swapping, the package startup time is longer
than without the swapping.
R1/R2 swapping using manual procedures
It is also possible to manually perform the R1/R2 swapping. In two scenarios Metrocluster with
EMC SRDF supports manual swapping.
R1/R2 swapping 63