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Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

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Establish an SRDF pair (full)

A full establish initiates the following activities for each specified SRDF pair in a device group, consistency group, storage group, or list of devices in a device file:

  1. The target (R2) device is write disabled to its local host I/O.
  2. Traffic is suspended on the SRDF links.
  3. All the tracks on the target (R2) device are marked invalid.
  4. All tracks on the R2 side are refreshed by the R1 source side. The track tables are merged between the R1 and R2 side.
  5. Traffic is resumed on the SRDF links.

In SRDF/S configurations, when the establish operation completes and the device pair is in the Synchronized state, the source (R1) device and the target (R2) device contain identical data.

In SRDF/A configurations, when the establish operation completes and the device pair is in the Consistent state, the target (R2) device contains dependent write consistent data.

In SRDF/Metro configurations, once the source (R1) device and the target(R2) device contain identical data, the pair state changes to either ActiveActive or ActiveBias and the R2 side is made RW-accessible to the host(s).

A full establish on SRDF pairs is required only:

  • At initial set-up of SRDF pairs.
  • When an R2 member of an SRDF pair is either fully invalid, or has been replaced.

The following image shows establishing an SRDF pair.

Figure 1. SRDF establish (full)
NOTE:

When you issue the symrdf command, device external locks are set on all SRDF devices you are about to establish. See Device external locks and Table 1.

NOTE:

The R2 may be set to read/write disabled (not ready) by setting the value of SYMAPI_RDF_RW_DISABLE_R2 to ENABLE in the options file. For more information, refer to the Dell Solutions Enabler CLI Reference Guide.

Syntax

Use establish -full for a device group, composite group, storage group, or device file: 

symrdf -g DgName establish -full 
symrdf -cg CgName establish -full
symrdf -sg SgName establish -full
symrdf -f[ile] FileName establish -full

Use the -use_bias option in SRDF/Metro configurations to indicate that neither the Witness nor the vWitness methods of determining bias is used: 

symrdf -g DgName establish -full -use_bias 
symrdf -cg CgName establish -full -use_bias
symrdf -sg SgName establish -full -use_bias
symrdf -f[ile] FileName establish -full -use_bias
NOTE:For SRDF/Metro configurations:
  • The establish operation must include all devices in the group.
  • If the Witness method is used to determine which side of the device pair remains accessible to the host, the Witness groups must be online or the vWitness must be accessible to both sides.

Create a device file describes the steps to create a device file.

Use the verify command to confirm that the SRDF pairs are in the correct state:

SRDF Mode State of the SRDF Pairs
Adaptive Copy Synchronized
SRDF/SynchronousSynchronized
SRDF/AsynchronousConsistent
SRDF/MetroActiveActive or ActiveBias

Examples

To establish all the SRDF pairs in the device group prod:

symrdf -g prod establish -full

To establish all the pairs in an SRDF/Metro group using bias:

symrdf -f /tmp/device_file -sid 085 -rdfg 86 establish -full -use_bias

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