Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

Step 3, option A: Create a composite group in Concurrent SRDF/Star

About this task

Follow these steps if the SRDF/Star configuration is a concurrent topology.

The following example procedure includes:

• A composite group named StarGrp,
• The workload site is NewYork,
• The synchronous target site is NewJersey, and
• The asynchronous target site is London.

NOTE:

Dell Solutions Enabler Array Controls and Management CLI User Guide provides additional information on composite groups and using the symcg -cg command.

Complete the following steps to build an RDF1 type composite group on the Star control host of the SRDF/Star workload site (NewYork, SID 11) in a concurrent configuration:

1. Determine which devices on the local array are configured as concurrent dynamic devices.

   To list the concurrent dynamic devices for array 11:

   symrdf list -sid 11 -concurrent -dynamic -both

   NOTE:

   Specify the -dynamic and -both options to display dynamic SRDF pairs in which the paired devices can be either R1 or R2 devices.

2. Create an RDF1-type composite group with consistency protection on the Star control host at the workload site.

   To create composite group StarGrp on array NewYork:

   symcg create StarGrp -type rdf1 -rdf_consistency

   NOTE:

   The -rdf_consistency option specifies consistency protection for the group.

3. Add devices to the composite group from those SRDF groups that represent the concurrent links for the SRDF/Star configuration.

   To add all the devices in SRDF groups 23 and 22 to composite group StarGrp:

   symcg -cg StarGrp -sid 11 addall dev -rdfg 23

   NOTE:

   With concurrent SRDF, the command that adds one of the two concurrent groups adds both concurrent groups (in this example, the synchronous SRDF group 22 is automatically added with the asynchronous SRDF group 23).

4. Create two SRDF group names; one for all synchronous links and one for all asynchronous links.

   To create two SRDF group names NewJersey for SRDF group 22 on SID 11 and SRDF group name London for SRDF group 23 on SID 11:

   symcg -cg StarGrp set -name NewJersey -rdfg 11:22
   symcg -cg StarGrp set -name London -rdfg 11:23

   NOTE:

   You could include additional synchronous SRDF groups in (synchronous) NewJersey using the sid:rdfg syntax. If the CG contains more than one triangle, you must issue the above command to set the SRDF group name for each additional SRDF group.

   You must also include the names NewJersey and London in the SRDF/Star options file as the values for the synchronous and asynchronous target site names, respectively.

   Step 4: Create the SRDF/Star options file provides more information.

5. For each source SRDF group that you added to the composite group, define a corresponding recovery SRDF group at the remote site.

   A recovery SRDF group can be static or dynamic, but it cannot be shared. A recovery SRDF group cannot contain any devices.

   In the following example for a non-R22 Star CG:

   • SRDF group 60 is an empty static or dynamic group on the remote array to which source SRDF group 22 is linked.
   • Recovery SRDF group 62 was configured on the other remote array as a match for the source SRDF group 23.

   To set the remote recovery group for StarGp RDF group 22 to SRDF group 60 at the remote site:

   symcg -cg StarGrp set -rdfg 11:22 -recovery_rdfg 60

   To set the remote recovery group for StarGp RDF group 23 to SRDF group 62 at the remote site:

   symcg -cg StarGrp set -rdfg 11:23 -recovery_rdfg 62

   These two recovery group definitions represent one recovery SRDF group as viewed from each of the two target sites.

   NOTE: If the CG contains more than one triangle, you must issue the above command to set the recovery group for each additional SRDF group.
6. Skip to Step 4: Create the SRDF/Star options file.