Sun Cluster Geographic Edition Data Replication Guide for Hitachi TrueCopy

Recovering Services to a Cluster on a System That Uses Hitachi TrueCopy Replication

After a successful takeover operation, the secondary cluster, cluster-newyork, becomes the primary for the protection group and the services are online on the secondary cluster. After the recovery of the original primary cluster,cluster-paris, the services can be brought online again on the original primary by using a process called failback.

Sun Cluster Geographic Edition software supports the following kinds of failback:

To continue using the new primary, cluster-newyork, as the primary cluster and the original primary cluster, cluster-paris, as the secondary after the original primary is running again, resynchronize and revalidate the protection group configuration without performing a switchover or takeover.

This section provides the following information:

ProcedureHow to Resynchronize and Revalidate the Protection Group Configuration

Use this procedure to resynchronize and revalidate data on the original primary cluster, cluster-paris, with the data on the current primary cluster, cluster-newyork.

Before You Begin

Before you resynchronize and revalidate the protection group configuration, a takeover has occurred on cluster-newyork. The clusters now have the following roles:

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

    cluster-paris forfeits its own configuration and replicates the cluster-newyork configuration locally. Resynchronize both the partnership and protection group configurations.

    1. On cluster-paris, resynchronize the partnership.


      # geops update partnershipname
      
      partnershipname

      Specifies the name of the partnership


      Note –

      You need to perform this step only once, even if you are resynchronizing multiple protection groups.


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

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

      Because the role of the protection group on cluster-newyork is primary, this step ensures that the role of the protection group on cluster-paris is secondary.


      # geopg update protectiongroupname
      
      protectiongroupname

      Specifies the name of the protection group

      For more information about synchronizing protection groups, see Resynchronizing a Hitachi TrueCopy Protection Group.

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


    # geopg validate protectiongroupname 
    
    protectiongroupname

    Specifies a unique name that identifies a single protection group

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

  3. On cluster-paris, activate each protection group.

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


    # geopg start -e local protectiongroupname
    
    -e local

    Specifies the scope of the command.

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

    protectiongroupname

    Specifies the name of the protection group.


    Caution – Caution –

    Do not use the -n option because the data needs to be synchronized from the current primary, cluster-newyork, to the current secondary, cluster-paris.


    Because the protection group has a role of secondary, the data is synchronized from the current primary, cluster-newyork, to the current secondary, cluster-paris.

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

  4. Confirm that the data is completely synchronized.

    The state of the protection group on cluster-newyork must be OK.


    phys-newyork-1# geoadm status
    

    Refer to the Protection Group section of the output.

    The protection group has a local state of OK when the Hitachi TrueCopy device groups on cluster-newyork have a state of PVOL_PAIR and the Hitachi TrueCopy device groups on cluster-paris have a state of SVOL_PAIR.

ProcedureHow to Perform a Failback-Switchover on a System That Uses Hitachi TrueCopy Replication

Use this procedure to restart an application on the original primary cluster, cluster-paris, after the data on this cluster has been resynchronized with the data on the current primary cluster, cluster-newyork.


Note –

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


Before You Begin

Before you perform a failback-switchover, a takeover has occurred on cluster-newyork. The clusters have the following roles:

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

    cluster-paris forfeits its own configuration and replicates the cluster-newyork configuration locally. Resynchronize both the partnership and protection group configurations.

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

      Because the local role of the protection group on cluster-newyork is now primary, this steps ensures that the role of the protection group on cluster-paris becomes secondary.


      phys-paris-1# geopg update protectiongroupname
      
      protectiongroupname

      Specifies the name of the protection group

      For more information about synchronizing protection groups, see Resynchronizing a Hitachi TrueCopy Protection Group.

  2. On cluster-paris, validate the cluster 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 an 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 Protection Group.

  3. On cluster-paris, activate each protection group.

    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 protectiongroupname
    
    -e local

    Specifies the scope of the command.

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

    protectiongroupname

    Specifies the name of the protection group.


    Caution – Caution –

    Do not use the -n option because the data needs to be synchronized from the current primary, cluster-newyork, to the current secondary, cluster-paris.


    Because the protection group has a role of secondary, the data is synchronized from the current primary, cluster-newyork, to the current secondary, cluster-paris.

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

  4. Confirm that the data is completely synchronized.

    The state of the protection group on cluster-newyork must be OK.


    phys-newyork-1# geoadm status
    

    Refer to the Protection Group section of the output.

    The protection group has a local state of OK when the Hitachi TrueCopy device groups on cluster-newyork have a state of PVOL_PAIR and the Hitachi TrueCopy device groups on cluster-paris have a state of SVOL_PAIR.

  5. On both partner clusters, ensure that the protection group is activated.


    # geoadm status
    
  6. On either cluster, perform a switchover from cluster-newyork to cluster-paris for each protection group.


    # geopg switchover [-f] -m clusterparis protectiongroupname
    

    For more information, see How to Switch Over a Hitachi TrueCopy Protection Group From Primary to Secondary.

    cluster-paris resumes its original role as primary cluster for the protection group.

  7. Ensure that the switchover 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 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 Data Replication.

ProcedureHow to Perform a Failback-Takeover on a System That Uses Hitachi TrueCopy 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 device group, devgroup1, in the SMPL state.

      Use the pairsplit commands to place the Hitachi TrueCopy 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 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

      For more information about the pairsplit commands, see the Sun StorEdge SE 9900 V Series Command and Control Interface User and Reference Guide.

      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 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 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 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 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 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 Data Replication.