Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

Table 22 Mapping for a 4 Node Cluster connected to 2 Symmetrix Arrays (continued)
Nodes 4 /dev/rdsk
device file name
Node 3 /dev/rdsk
device file name
Node 2 /dev/rdsk
device file name
Node 1 /dev/rdsk
device file name
Symmetrix ID,
device #, and type
c4t3d295ID
c4t3d2028Dev#
n/an/aBCVType
NOTE: The Symmetrix device number may be the same or different in each of the Symmetrix
units for the same logical device. In other words, the device number for the logical device on the
R1 side of the SRDF link may be different from the device number for the logical device on the R2
side of the SRDF link.
The Symmetrix logical device numbers in these examples were configured to be the same number
so the cluster is easier to manage. If reconfiguring an existing cluster, the Dev and RDev devices
will probably not be the same number.
When determining the configuration for the Symmetrix devices for a new installation, it is
recommended to use the same Symmetrix device number for both the R1 and R2 devices. It is also
recommended the same target and LUN number be configured for all nodes that have access to
the same Symmetrix logical device.
Building a Metrocluster Solution with EMC SRDF
Setting up 1 by 1 Configurations
The most common Symmetrix configuration used with Metrocluster with EMC SRDF is a 1 by 1
configuration in which there is a single Symmetrix frame at each Data Center. This section describes
how to set up this configuration using EMC Solutions Enabler and HP-UX commands. It is assumed
the Symmetrix CLI database is already set up on each node, as described in the previous section
“Preparing the Cluster for Data Replication.”
A basic 1 by 1 configuration is shown in Figure 45, which is a graphical view of the data in
Table 22.
Figure 45 Mapping HP-UX Device File Names to Symmetrix Units
Creating Symmetrix Device Groups
A single Symmetrix device group must be defined for each package on each node that is connected
to the Symmetrix. The following procedure must be done on each node that may potentially run
the package:
NOTE: The sample scripts mk3symgrps.nodename can be modified to automate these steps.
1. Use the symdg command, or modify the mk3symgrps.nodename script to define an R1 and
an R2 device group for each package.
# symdg create -type RDF1 devgroupname
262 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF