Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

Step 3, option B: Create a composite group in Cascaded SRDF/Star

About this task

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

The following example procedure includes:

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

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 cascaded environment:

1. Determine which devices on the local array (-sid 11) are configured as cascaded dynamic devices.

   To list the cascaded dynamic devices for array 11:

   symrdf list -sid 11 -R1 -cascaded -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 NewYork:

   symcg create StarGrp -type rdf1 -rdf_consistency

   NOTE:

   Specify the -rdf_consistency option to specify consistency protection for the group.

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

   To add devices in SRDF group 22 to composite group StarGrp:

   symcg -cg StarGrp -sid 11 addall dev -rdfg 22

4. Create one SRDF group name for all synchronous links.

   To create SRDF group name NewJersey for devices in SRDF group 22 on SID 11:

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

   NOTE:

   The site named NewJersey includes synchronous SRDF group 22 on array 11. 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.

   Include the site 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 added to the composite group, define a corresponding recovery SRDF group at the local (workload) site.

   The recovery SRDF group:

   • Can be static or dynamic.
   • Cannot be shared.
   • Cannot contain any devices.
   • Must be empty.

   For the cascaded setup in Figure 1, the recovery SRDF group is the empty SRDF group 23 configured between the NewYork synchronous site and the London asynchronous site.

   To add this recovery SRDF group:

   symcg -cg StarGrp set -rdfg 11:22 -recovery_rdfg 23