Performing failback after a node failure or an application failure
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Performing failback after a node failure or an application failure

Review the details on node failure and application failure and how VCS and the agent for EMC SRDF behave in response to these failures.

See Failure scenarios in global clusters.

See Failure scenarios in replicated data clusters.

After the nodes at the primary site are restarted, you can perform a failback of the global service group to the primary site. Depending on your DR configuration, perform one of the following procedures.

To perform failback after a node failure or an application failure in global cluster

  1. Switch the global service group from the secondary site to any node in the primary site.
    hagrp -switch global_group -any -clus cluster_name

    VCS brings the global service group online at the primary site.

    The VCS agent for EMC SRDF does the following based on whether the RDF pairs are static or dynamic:

    For dynamic RDF

    Based on the value of the SwapRoles attribute of the SRDF resource:

    • 1 - Write enables the devices at the primary site, swaps the R1/R2 personality of each device in the device group or the consistency group, and restarts replication from R1 devices on the primary site to the R2 devices at the secondary site.

    • 0 - Issues the symrdf failback command to resync the R1 devices and to write enable the R1 devices at the primary site.

    For static RDF

    Issues the symrdf failback command to resync the R1 devices and to write enable the R1 devices at the primary site.

  2. Verify that the SRDF devices at the primary site are write-enabled and the device state is SYNCHRONIZED or CONSISTENT.

To perform failback after a host failure or an application failure in replicated data cluster

  1. Switch the global service group from the secondary site to any node in the primary site.
    hagrp -switch service_group -to sys_name

    VCS brings the global service group online on a node at the primary site.

    The VCS agent for EMC SRDF does the following based on whether the RDF pairs are static or dynamic:

    For dynamic RDF

    Based on the value of the SwapRoles attribute of the SRDF resource:

    • 1 - Write enables the devices at the primary site, swaps the R1/R2 personality of each device in the device group or the consistency group, and restarts replication from R1 devices on the primary site to the R2 devices at the secondary site.

    • 0 - Issues the symrdf failback command to resync the R1 devices and to write enable the R1 devices at the primary site.

    For static RDF

    Issues the symrdf failback command to resync the R1 devices and to write enable the R1 devices at the primary site.

  2. Verify that the SRDF devices at the primary site are write-enabled and the device state is SYNCHRONIZED or CONSISTENT.

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