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Sun Cluster Geographic Edition Data Replication Guide for Hitachi TrueCopy and Universal Replicator

ProcedureHow to Perform a Failback-Takeover on a System That Uses Hitachi TrueCopy or Universal Replicator Replication

Use this procedure to restart an application on the original primary cluster, cluster-paris, and use the current data on the original primary cluster. Any updates that occurred on the secondary cluster, cluster-newyork, while it was acting as primary are discarded.

The failback procedures apply only to clusters in a partnership. You need to perform the following procedure only once per partnership.

Note –

Conditionally, you can resume using the data on the original primary, cluster-paris. You must not have replicated data from the new primary, cluster-newyork, to the original primary cluster, cluster-paris, at any point after the takeover operation on cluster-newyork. To prevent data replication between the new primary and the original primary, you must use the -n option when you run the geopg start command.

Before You Begin

Ensure that the clusters have the following roles:

  1. Resynchronize the original primary cluster, cluster-paris, with the original secondary cluster, cluster-newyork.

    cluster-paris forfeits its own configuration and replicates the cluster-newyork configuration locally.

    1. On cluster-paris, resynchronize the partnership.


      phys-paris-1# geops update partnershipname
      partnershipname

      Specifies the name of the partnership

      Note –

      You need to perform this step only once per partnership, even if you are performing a failback-takeover for multiple protection groups in the partnership.

      For more information about synchronizing partnerships, see Resynchronizing a Partnership in Sun Cluster Geographic Edition System Administration Guide.

    2. Determine whether the protection group on the original primary cluster, cluster-paris, is active.


      phys-paris-1# geoadm status

    3. If the protection group on the original primary cluster is active, stop it.


      phys-paris-1# geopg stop -e local protectiongroupname

    4. Verify that the protection group is stopped.


      phys-paris-1# geoadm status

    5. Place the Hitachi TrueCopy or Universal Replicator device group, devgroup1, in the SMPL state.

      Use the pairsplit commands to place the Hitachi TrueCopy or Universal Replicator device groups that are in the protection group on both cluster-paris and cluster-newyork in the SMPL state. The pairsplit command you use depends on the pair state of the Hitachi TrueCopy or Universal Replicator device group. The following table gives some examples of the command you need to use on cluster-paris for some typical pair states.

      Pair State on cluster-paris

      Pair State on cluster-newyork

      pairsplit Command Used on cluster-paris

      PSUS or PSUE

      SSWS

      pairsplit -R -g dgname

      pairsplit -S -g dgname

      SSUS

      PSUS

      pairsplit -S -g dgname

      If the command is successful, the state of devgroup1 is provided in the output of the pairdisplay command:


      phys-paris-1# pairdisplay -g devgroup1
Group PairVol(L/R) (Port#,TID,LU),Seq#,LDEV#,P/S,Status,Fence,Seq#,P-LDEV# M 
devgroup1 pair1(L) (CL1-A , 0, 1) 12345   1..SMPL ----  ----,-----  ----   - 
devgroup1 pair1(R) (CL1-C , 0, 20)54321 609..SMPL ----  ----,-----  ----   - 
devgroup1 pair2(L) (CL1-A , 0, 2) 12345   2..SMPL ----  ----,-----  ----   - 
devgroup1 pair2(R) (CL1-C , 0,21) 54321 610..SMPL ----  ----,-----  ----   -

      .

    6. On cluster-paris, resynchronize each protection group.


      phys-paris-1# geopg update protectiongroupname
      protectiongroupname

      Specifies the name of the protection group

      For more information about resynchronizing protection groups, see How to Resynchronize a Protection Group.

  2. On cluster-paris, validate the configuration for each protection group.

    Ensure that the protection group is not in an error state. A protection group cannot be started when it is in a error state.


    phys-paris-1# geopg validate protectiongroupname
    protectiongroupname

    Specifies a unique name that identifies a single protection group

    For more information, see How to Validate a Hitachi TrueCopy or Universal Replicator Protection Group.

  3. On cluster-paris, activate each protection group in the secondary role without data replication.

    Because the protection group on cluster-paris has a role of secondary, the geopg start command does not restart the application on cluster-paris.


    phys-paris-1# geopg start -e local -n protectiongroupname
    -e local

    Specifies the scope of the command

    .

    By specifying a local scope, the command operates on the local cluster only.

    -n

    Prevents the start of data replication at protection group startup.

    Note –

    You must use the -n option.

    protectiongroupname

    Specifies the name of the protection group.

    For more information, see How to Activate a Hitachi TrueCopy or Universal Replicator Protection Group.

    Replication from cluster-newyork to cluster-paris is not started because the -n option is used on cluster-paris.

  4. On cluster-paris, initiate a takeover for each protection group.


    phys-paris-1# geopg takeover [-f] protectiongroupname
    -f

    Forces the command to perform the operation without your confirmation

    protectiongroupname

    Specifies the name of the protection group

    For more information about the geopg takeover command, see How to Force Immediate Takeover of Hitachi TrueCopy or Universal Replicator Services by a Secondary Cluster.

    The protection group on cluster-paris now has the primary role, and the protection group on cluster-newyork has the role of secondary. The application services are now online on cluster-paris.

  5. On cluster-newyork, activate each protection group.

    At the end of step 4, the local state of the protection group on cluster-newyork is Offline. To start monitoring the local state of the protection group, you must activate the protection group on cluster-newyork.

    Because the protection group on cluster-newyork has a role of secondary, the geopg start command does not restart the application on cluster-newyork.


    phys-newyork-1# geopg start -e local [-n] protectiongroupname
    -e local

    Specifies the scope of the command.

    By specifying a local scope, the command operates on the local cluster only.

    -n

    Prevents the start of data replication at protection group startup.

    If you omit this option, the data replication subsystem starts at the same time as the protection group.

    protectiongroupname

    Specifies the name of the protection group.

    For more information about the geopg start command, see How to Activate a Hitachi TrueCopy or Universal Replicator Protection Group.

  6. Ensure that the takeover was performed successfully.

    Verify that the protection group is now primary on cluster-paris and secondary on cluster-newyork and that the state for “Data replication” and “Resource groups” is OK on both clusters.


    # geoadm status

    Check the runtime status of the application resource group and data replication for each Hitachi TrueCopy or Universal Replicator protection group.


    # clresourcegroup status -v
# clresource status -v

    Refer to the Status and Status Message fields that are presented for the data replication device group you want to check. For more information about these fields, see Table 2–1.

    For more information about the runtime status of data replication, see Checking the Runtime Status of Hitachi TrueCopy and Universal Replicator Data Replication.