Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

Creating a consistency group

1. Use the symcfg list command to list all SRDF (RA) groups on the source arrays connected to the local hosts to determine which devices to include in the CG:

   symcfg list -rdfg all

2. Use the symcg create command to create a consistency group (ConsisGrp) on one of the local hosts.

   Specify the SRDF type of the group and the -rdf_consistency option:

   symcg create ConsisGrp -type rdf1 -rdf_consistency

3. Use the symcg addall command to add the devices from an SRDF (RA) group, such as RDG 64 , into the consistency group (ConsisGrp) :

   symcg -cg ConsisGrp -sid 3264 addall dev -rdfg 64

4. In a database configuration with multiple local hosts, you must build the same consistency group on all local hosts in the configuration.

   You can use the symcg export command to manually transfer the consistency group definition, or if enabled, use GNS to automatically transfer it.

   The following commands create the consisgrp.txt text file containing the new ConsisGrp composite group definition and then transfer it to Host-1:

   symcg export ConsisGrp -f consisgrp.txt

   rcp consisgrp.txt Host-1:/.

   In the following command, the -rdf_consistency option adds the imported ConsisGrp definition to the SRDF consistency database on Host-1:

   symcg import ConsisGrp -f consisgrp.txt -rdf_consistency

5. Verify that all devices in the group are either all synchronous or all asynchronous.

   symrdf -cg ConsisGrp verify -async

6. If the devices are currently operating with synchronous replication and you want them to be operating asynchronously, set the composite group for asynchronous replication:

   symrdf -cg ConsisGrp set mode async

7. If the SRDF pairs are not in the Consistent or Synchronized state at this time (the Split or Suspended state), you can use the symrdf establish command to initiate SRDF copying of R1 data to the R2 side.

   symrdf -cg ConsisGrp establish

   The device state is SyncInProg until the Consistent or Synchronized state is reached.

   With asynchronous replication, it may take two cycle switches for all devices to reach the Consistent state.

   In multi-cycle mode, if either the link is or destaging the R2Apply cycle is slow, it may take more than 2 cycle switches for all devices to reach Consistent state.

8. From one of the local hosts, use the symcg enable command to enable the composite group for consistency protection:

   symcg -cg ConsisGrp enable

   The ConsistGrp CG becomes an SRDF consistency group managed by the SRDF daemon.

   The SRDF daemon watches for any problems with R1->R2 data within the ConsistGrp CG.