Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

If an R1 device in a CG cannot send data to its R2 target, the SRDF links for only those devices in the specified SRDF group of the CG are suspended.

SRDF group protection is useful for concurrent devices with one mirror operating in synchronous mode and the other mirror operating in asynchronous mode.

To enable consistency protection at the SRDF group name level, you must first define one or more named subsets of devices within the composite group.

A subset can consist of one or more of the SRDF groups within the composite group.

Restrictions

When a subset of a CG is enabled for consistency protection at the SRDF group name level:

• You must disable consistency protection on the subset before you can:
  • Change the name of the subset.
  • Add or remove SRDF groups to the subset.
    NOTE:

    For an RDF1 composite group, you can dynamically modify the contents of a subset while consistency protection is enabled. Modify consistency groups provides more information.

• You cannot enable a composite group at the CG level and a member SRDF group at the same time.
  • If a composite group is enabled at the CG level, no part of it can be simultaneously enabled at the SRDF group name level.
  • If a subset of the group is enabled at the SRDF group name level, the group cannot be enabled at the CG level.

Examples

In the following example, composite group SALES consists of a set of concurrent SRDF devices distributed across two arrays, 076 and 077.

• On array 076:
  • SRDF group 100 operates in asynchronous mode, and
  • SRDF group 120 operates in synchronous mode.
• On array 077:
  • SRDF group 101 operates in asynchronous mode, and
  • SRDF group 121 operates in synchronous mode.

To create two named subsets of the composite group:

One containing the asynchronous SRDF groups:

symcg -cg SALES set -name sales1 -rdfg 76:100
symcg -cg SALES set -name sales1 -rdfg 77:101

One containing the synchronous SRDF groups:

symcg -cg SALES set -name sales2 -rdfg 76:120
symcg -cg SALES set -name sales2 -rdfg 77:121

To enable independent consistency protection for the two subsets:

symcg -cg SALES enable -rdfg name:sales1
symcg -cg SALES enable -rdfg name:sales2

symcg -cg [groupname] set -name -rdfg
XX:YY