Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF

The following examples are based on the configuration shown in Figure 4.

For each package, to create consistency groups:

1. On each node in the cluster, create an empty consistency group using the symcg command.

To create a consistency group using PowerPath on the R1 side, run the following command:

# symcg create cgoradb -ppath -type rdf1

Replace rdf1 with rdf2 in the command to create the consistency group on the R2 side.

To create a consistency group using RDF-ECA on the R1 side, run the following command:

# symcg create cgoradb -rdf_consistency -type rdf1

Replace rdf1 with rdf2 in the command to create the consistency group on the R2 side.

Use the same name on all the nodes.

To use RDF-ECA, ensure that the RDF process daemon is running on any of the locally attached

hosts. For redundancy, it is recommended that you run multiple instances of the RDF daemon

on different hosts. For more information about configuring and using RDF-ECA, see the EMC

documentation website.

2. Add each device that is going to be used in the consistency group. Use the appropriate SID

numbers and device names for the data center that the node is a part of. For example, on

node1 and node2 in Data Center A.

# symcg -cg cgoradb -sid 638 add dev 00C

# symcg -cg cgoradb -sid 638 add dev 00D

# symcg -cg cgoradb -sid 130 add dev 010

# symcg -cg cgoradb -sid 130 add dev 011

And on node3 and node4 in Data Center B.

# symcg -cg cgoradb -sid 021 add dev 018

# symcg -cg cgoradb -sid 021 add dev 019

# symcg -cg cgoradb -sid 363 add dev 050

# symcg -cg cgoradb -sid 363 add dev 051

3. Enable the consistency group.

# symcg -g cgoradb enable

NOTE: This important step must be carried out on every node.

4. Establish the BCV devices in the secondary Symmetrix as a mirror of the standard device.

From either node3 or node4, run the following commands:

# symmir -cg cgoradb -full est

Alternatively, from either node1 or node2, run the following command:

# symmir -cg cgoradb -full est -rdf

Configuring SRDF/Asynchronous Multi-Session Consistency (MSC) data replication

In order to provide a consistent, restartable local copy of data spanning across two local Symmetrix

volumes, a composite group is configured. A composite group is similar to device group but can

contain devices spanning across multiple Symmetrix arrays and multiple RDF(RA) groups. An SRDF

consistency group is a composite group with special properties to allow SRDF devices in separate

SRDF groups to maintain dependent write order consistency. The following sections describe the

steps for building a consistency group in a SRDF/Asynchronous MSC environment

24 Configuring an application in a Metrocluster solution