Building Disaster Tolerant Serviceguard Solutions Using Metrocluster with EMC SRDF
Building a Metrocluster Solution with EMC SRDF
Chapter 5 323
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 should
be Synchronized for SRDF/Synchronous or Consistent for
SRDF/Asynchronous when the re-sync is completed. Check the state and
ensure that the re-sync is completed before enabling the package switch.
If Metrocluster with EMC SRDF is used in Continentalclusters, it is not
necessary to disable the package switch on the nodes on recovery site
since each site has its own cluster. However, when the re-sync is in
progress, make sure the recovery site will not start the recovery
operation in the event of a disaster occurring on the primary site. Use
the following procedures to protect data consistency on R2 in a
Continentalclusters environment:
1. Split the BCV in the secondary Symmetrix from the mirror group to
save a good copy of the data from nodes on R2 side:
# symmir -g dgname split
Alternatively, from node on R1 side.
# symmir -g dgname split -rdf
2. Begin to resynchronize the data from R1 to R2 devices.
# symrdf -g dgname est
3. Re-establish the BCV to R2 devices on R2 as a mirror.
# symmir -g dgname -full est
Alternatively, from node on R1 side.
# symmir -g dgname -full est -rdf
R1/R2 Swapping
This section describes how the R1/R2 swapping can be done via the
Metrocluster SRDF package and manual procedures. Each of these
methods allows swapping the SRDF personality for each device
designation of a specified device group. In this situation, each source R1
device(s) becomes a target R2 device(s), and a target R1 device(s)
becomes a source R1 device(s).