SRDF/A

Setting Up SRDF Asynchronous Operation
The following steps outline the procedure for performing SRDF control operations with SRDF Asynchronous (SRDF/A) replication (for outputs to these commands, refer to Example 5):

1. Determine which devices should belong to the device group or composite group by first listing all RDF (RA) groups on the source Symmetrix arrays connected to the local host (symcfg list). Beginning with Solutions Enabler version 6.0, all RDF groups on a Symmetrix array are capable of SRDF/A operation (prior versions required that you configure an RDF group to be capable of SRDF/A). To display devices within a particular RDF group, use the symrdf list command with the RDF group number (for example, RDF group 64).

symcfg list -rdfg all symrdf list -rdfg 64

2. The following command creates an RDF1 type device group named AsyncGrp1:

symdg create AsyncGrp1 -type rdf1

3. Add to the device group all devices from one RDF (RA) group. (If using a composite group, you can add devices from multiple RDF (RA) groups.) For example, if you choose RDF group number 64, then all devices in this RDF group will be managed for SRDF/A operation.

symld -g AsyncGrp1 addall -rdfg 64

4. Set the device group to Asynchronous replication:

symrdf -g AsyncGrp1 set mode async

5. If the SRDF pairs are not in the Consistent state at this time (for example, the Split or Suspended state with invalid tracks on the R1 side), you can initiate SRDF copying of R1 data to the R2 side. The device state will be SyncInProg until the Consistent state is reached.

symrdf -g AsyncGrp1 establish

6. Enable consistency protection for the SRDF/A devices in the device group:

symrdf -g AsyncGrp1 enable

7. If you need to manually trip the device group, you can suspend the RDF links for the device group or split the SRDF pairs. By default, the SRDF/A session is dropped at the next switch in copy cycles. The SRDF/A session becomes inactive. The -force option is required to ensure that you actually want to stop SRDF/A operation and end consistency protection.

symrdf -g AsyncGrp1 suspend -force

8. If there are writes to the R1 source devices while the SRDF/A session is inactive, invalid R1 tracks will accumulate on the R1 side. These are tracks that are owed to the R2 side. If the devices are made ready on the link, you can resume SRDF operation, copying these tracks to the R2 side. The SRDF/A session is automatically activated.

symrdf -g AsyncGrp1 resume

At this point, the SRDF/A devices are ready on the RDF link and operating with Asynchronous replication. Consistency protection remains set.