Converting Global Mirror legacy replication to policy-based asynchronous disaster recovery replication

If you currently replicate data between two partnered systems by using Global Mirror, you can convert the current configuration to policy-based replication. The remote-copy configuration can remain in place for a volume while the volume is configured with policy-based replication, so there is no period without a synchronized copy in place on the DR system. Relationships or Consistency Groups that use Global Mirror with Change Volumes must be converted to Global Mirror to allow a migration to policy-based replication.

Policy-based replication supports asynchronous replication between two systems. If you currently use Global Mirror or Global Mirror with change volumes configurations to replicate data between two systems, it is possible to convert to policy-based replication from these configurations. Other remote copy functions, like 3-site partnerships, nondisruptive volume migration, and Metro Mirror cannot be converted to policy-based replication without first converting any relationships to Global Mirror.

Using the management GUI

To convert Global Mirror replicated volumes to use policy-based replication, complete these tasks:
Update the current partnership to use policy-based replication
To update the partnership, complete these steps:
  1. On the local system, select Copy Services > Partnerships and Remote Copy.
  2. Select the current remote copy partnership from the left navigation and select Actions > Partnership Properties.
  3. On the Partnership Properties page, select Enable for policy-based replication to retrieve the certificate from the remote system. The management GUI automatically creates a truststore on the local system to store the certificate from the remote system.
    Note: If you are using the command-line interface, you must create a truststore on each system in the partnership.
    View the certificate to verify that the remote system certificate is correct.
  4. Click Save.
  5. On the local system, the following error message displays: Policy-based replication issue. In this case, the error is expected because the partnership on the remote system is not enabled for policy-based replication.
  6. Repeat these steps on the remote system in the partnership.
  7. After remote system is enabled for policy-based replication, verify that the partnership can be configured use policy-based replication. On one of the systems, select Copy Services > Partnerships and Remote Copy and select the partnership from the left navigation. The message This partnership is ready for use with policy-based replication displays.
Create pool links between systems
If pools currently exist on a system in the partnership, create linked pools on the system where you want data to be replicated. For example, if pools exist on the production system, access the recovery system and create links. If the pools are on the recovery system, create links on the production system. To create pool links, see Creating linked pools.
Configure a provisioning policy for each linked pool (optional)
For policy-based replication, a provisioning policy can be used to control how capacity is provisioned on new volumes in the linked pools. If a provisioning policy is not configured on a pool, the system automatically creates fully provisioned volumes. You can assign a provisioning policy to a pool in the management GUI on the Pools page, or when you create links between pools. Linked pools can be assigned to provisioning policies with different capacity savings methods, allowing different types of pools to be linked. The system creates two default provisioning policies when the first parent pool is created. You can create more user-defined policies to specify alternative capacity savings.

For more information, see Creating provisioning policy and assigning to pools.

Create one or more replication policies
For configurations with more than two I/O groups, you can move volumes to the I/O groups that are defined in the new replication policies after volumes are removed from the remote copy configuration.

You might need multiple replication policies depending on your current configuration of remote-copy relationships and consistency groups. For example, if you currently use Global Mirror with change volumes, you might have different RPO values for different types of data. For each RPO, you can create a different replication policy. For more information, see Creating replication policies.

Identify the Global Mirror consistency groups and relationships on the production system
To determine the Global Mirror consistency groups, complete these steps:
  1. In the management GUI, select Copy Services > Partnerships and Remote Copy.
  2. On the Consistency Group tab, identify the consistency groups that are used for Global Mirror replication.
  3. Select the consistency group to display a list of relationships in that group.
  4. Right-click the column heading and select Primary Volume to determine the primary volumes for each relationship that is displayed. These volumes are added to the volume group.
  5. The cycling mode must be set to none and the primary change volume must be removed from each relationship. The consistency group must be in a stopped state to change the cycling mode. If there is insufficient bandwidth to replicate using non-cycling Global Mirror, the consistency group can remain in a stopped state.
  6. If necessary, select the Export to CSV icon to download CSV of the table.

To determine the independent relationships, complete these steps:

  1. In the management, select Copy Services > Partnerships and Remote Copy.
  2. For independent relationships, select the Independent Relationship tab.
  3. Right-click the column heading and select Primary Volume to determine the primary volumes for each relationship that is displayed. These volumes will be added to the volume group. You can also filter the table on names that are related to the volume or relationships.
  4. The cycling mode must be set to none and the primary change volume must be removed from the relationship. The relationship must be in a stopped state to change the cycling mode. If there is insufficient bandwidth to replicate using non-cycling Global Mirror, the relationship can remain in a stopped state.
  5. If necessary, select the Export to CSV icon to download CSV of the table.
Create an empty volume group for each consistency group and independent relationships and assign a replication policy
On the production system, create empty volume groups for each consistency group or create one or more volume groups for each independent relationship. Unlike with remote copy replication, this step is only required on the production system. With policy-based replication, the production system manages provisioning on the remote system. After volume groups are created, assign the replication policy by completing these steps:
  1. In the management GUI, select Volumes > Volumes Groups.
  2. Click Create Volume Group.
  3. On the Create Volume Group page, enter the volume group name. This volume group replaces the consistency group in the remote-copy configuration.
  4. Click Create Empty Group.
  5. On the Volume Groups page, select the volume group that was created.
  6. On the Policies tab, click Assign replication policy.
  7. On the Assign Replication Policy page, select the replication policy that you created earlier and click Assign.
Remove remote copy configuration (optional)
Before you remove the remote copy configuration, determine whether to retain existing secondary volumes as a point-in-time copy for disaster recovery until the new recovery copy is established with policy-based replication. If you keep a disaster recovery copy, ensure that you have enough capacity available on the recovery system to accommodate both sets of copies. By retaining existing volumes, you protect data if an outage occurs. You can also verify the replicated data on the recovery system after policy-based replication is configured.
Tip:
  • You can skip this task if you don't have enough capacity or resources to maintain two relationship copies for the volume.
  • You can remove the remote-copy configuration after the volume group for policy-based replication completes its initial sync.
To remove consistency groups, complete these steps:
  1. On primary system, select Copy Services > Partnerships and Remote Copy.
  2. Select the Consistency Group tab, verify that the current state of the consistency group is Consistent Synchronized, Consistent Copying or Consistent Stopped.
  3. Select Actions > Stop Group.
  4. On the Stop Remote-Copy Consistency Group page, select Allow secondary read/write access, retaining the secondary volumes as a disaster recovery copy.
    Note: If you do not want to retain secondary copies as a disaster recovery copy, you can delete them from the remote system.
  5. Click Stop Consistency Group. The state of the consistency group changes to Idling.
  6. In the Relationships section, select all the relationships in the consistency group.
  7. Right-click the selected relationships and select Delete.
  8. On the Delete Relationship page, verify the number of relationships you are deleting. Ensure the checkbox to Delete the relationship even when the data on the target system is not consistent is not selected. This checkbox allows the secondary volumes to be retained for disaster recovery until a new recovery point is established that uses policy-based replication.
  9. Click Delete.
  10. After the relationships are deleted from the consistency group, select Actions > Delete Group.
To remove independent relationships, complete these steps:
  1. On primary system, select Copy Services > Partnerships and Remote Copy.
  2. Select the Independent Relationship tab, verify that the current state of the relationship is Consistent Synchronized, Consistent Copying or Consistent Stopped.
  3. Right-click the relationship and select Stop.
  4. On the Stop Remote-Copy Relationship page, select Allow secondary read/write access.
  5. Click Stop Relationship. This action allows access to the secondary volumes as a disaster recovery copy.
  6. Select Actions > Delete.
Move the volumes into the volume groups on the production system
The system will automatically configure on the volumes according to the replication policy of the group. To move volumes into the volume group, complete these steps:
  1. In the management GUI, select Volumes > Volumes Groups.
  2. Select the volume group that you want to add the volumes to and select Actions > Add Existing Volumes.
  3. On the Add Existing Volumes page, select primary volumes that you identified earlier and add them to the volume group and click Add Existing Volumes.
Verify policy-based replication
To verify replication is active for the volume groups, complete these steps:
  1. On the either the production or recovery system, select Volumes > Volume Groups.
  2. In the volume group table, verify that the replication state is Replication running. If you want to see additional information about the replication state, select a volume group and select the Policies tab.
  3. When the recovery copy has been established for the volume group using policy-based replication, the previous secondary volumes can be deleted.