Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Physical Data Replication for ContinentalClusters Using EMC SRDF
Preparing a Continental Cluster for Data Replication
Chapter 7 331
7. Use the symdg, symld and symgate commands on all nodes in both
clusters. to create the Symmetrix device groups. All devices
belonging to volume groups that are owned by an application
package must be defined in a single Symmetrix device group. The
device group name must be the same on both R1 side and the R2 side
of the SRDF link. A unique Symmetrix gatekeeper device should be
created for each application package.
When creating the Symmetrix device groups, you may specify only
one HP-UX path to a particular Symmetrix device. Do not specify
alternate paths (PVLinks). The SymCLI uses the HP-UX path only
to determine to which Symmetrix device you are referring. The
Symmetrix device may be added to the device group only once.
Use only the default Symmetrix Logical Device names of the form
"DEVnnn" (e.g., DEV001). Do not use the option for creating your own
device names.
See the scripts in the Samples-CC directory for examples of how you
would use these commands to build the SymCLI database and setup
the Symmetrix device groups. The sample scripts are:
• mk3symgrps.<hostname>
• mk4gatekpr.<hostname>
The script must be customized for each system in both clusters.
Customizations include:
• particular special device file names
• Symmetrix device group name (arbitrary, but unique name may
be chosen for each group that defines all of the volume groups
(VGs) belonging to a particular MC/ServiceGuard package)
• keyword RDF1 or RDF2
Gatekeeper devices must be unique per MC/ServiceGuard
package to prevent contention in the Symmetrix when
commands are issued. Gatekeeper devices are unique to a
Symmetrix unit. They are not replicated across the SRDF link.
There should be at least two gatekeeper devices accessible from each
host system. Each gatekeeper device is configured on different
physical links. The SymCLI will switch to an alternate gatekeeper
device if the path to the primary gatekeeper device fails.