Migrating from SVC Global Mirror or Global Mirror with Change Volumes to Asynchronous Policy-Based Replication with Limited Bandwidth or Storage Capacity (7.4)

Background

Asynchronous Policy-based replication is a technology that is designed to be a replacement to Global Mirror and Global Mirror with Change volumes. Policy-based replication is designed to provide both simplified configuration and management by assigning a set of volumes to a volume group, and assigning a replication policy to the volume group.

Before you begin

This scenario assumes that the following tasks have been completed prior to these steps:

• A cluster between the nodes has been created, and the cluster nodes have a status of Active.

• An existing PowerHA Global Mirror or Global Mirror with Change Volumes environment is configured.

• The storage software is at a level that supports both PowerHA Policy-based replication and prior Global Mirror technologies.

Procedure

Enabling Asynchronous Policy-Based Replication in the Storage

Configuring the Storage Controller Partnership for Policy-Based Replication

If you have not configured the systems for policy-based replication, it must be enabled on the partnership properties.

1. Log into the primary storage controller web interface.

2. Click Copy Services → Partnerships and Remote Copy.

3. View the partnership properties.

4. Look for Policy-based replication enabled on the partnership properties screen. If it is not enabled, move the slider to enable policy-based replication.

5. Repeat steps 1-4 on the target storage controller web interface to enable policy-based replication on both storage controllers.

Configuring the Storage Pool Provisioning Policy and Link

If you have not previously set storage pool provisioning policies and storage pool links, they must be created.

1. Log into the primary storage controller web interface.

2. Create a provisioning policy if one does not already exist.

3. Assign the provisioning policy to the storage pool that has the IASP volumes.

4. Log into the target storage controller and repeat steps 2 and 3.

5. Back on the primary storage controller link the storage pools.

The pool will contain an indication it is linked and a provisioning policy.

Open

Removing the Global Mirror Configuration

1. End PowerHA’s Management of the Global Mirror consistency group by ending PowerHA’s Global Mirror session. Use the PowerHA command ENDSVCSSN. For example, ENDSVCSSN SSN(MYSSN)

2. Log into the source storage system with a user that has enough authority.

   1. Click Copy Services → Partnerships and Remote Copy.

   2. Click on the partnership that contains the Global Mirror consistency group.

   3. Click on the Consistency Groups tabs.

   4. Use the action to stop the consistency group. There is no need to enable secondary read/write access.

   5. Delete the consistency group using the delete option. This makes all of the relationships that were in the group independent relationships.

   6. Click on the Independent Relationships tab.

   7. Select the remote copy relationships that were previously in the consistency group that was just deleted, and right-click and select delete to delete the relationships, double-checking the correct relationships are being deleted when confirming.

   8. If the replication was previously using Global Mirror with Change Volumes, delete the change volumes from the primary storage controller, being careful to select the right volumes for deletion.

3. Log into the target storage system web interface with a user that has enough authority.

   1. Remove the host mappings for the target Global Mirror Volumes

      1. Log into the target storage controller with a user that has enough authority.

      2. Click on Volumes → Volumes by Hosts and Clusters.

      3. Locate the target host in the storage.

      4. Select the IASP volumes. Using shift+click or ctrl+click enables the selection of multiple consecutive or additional volumes.

      5. Click on Actions → Remove Private Mappings …

      6. Confirm the mappings being removed and click Remove.

   2. Click on volumes to go to the list of volumes.

   3. Locate the volumes that were previously used as the target of global mirror. Be careful to select the right volumes for deletion. These volumes should not be assigned to a host.

   4. Delete the volumes that were previously target volumes for global mirror.

   5. If the replication was previously using Global Mirror with change volumes, delete the target change volumes as well, being careful once again to select the right volumes for deletion.

Configuring Policy-Based Replication

1. Log into the primary storage system with a user that has enough authority.

2. If you have not already created a replication policy in the storage, create a replication policy

3. If the Independent ASP volumes are not already in a volume group in the storage, create a volume group

4. Assign a replication policy to the volume group.

5. Wait for the initial copy to complete. Because Global Mirror is still processing as well, we still have a consistent copy we can switch to with Global Mirror while waiting for this process to complete.

Modify Volume Mappings on the Target System

This process maps the new Policy-Based Replication Volumes to the target IBM i.

Add the new Policy-Based replication Volumes

1. Log into the target storage controller with a user that has enough authority.

2. Click on Volumes → Volume Groups.

3. Click on the volume group name to view details for the volume group.

4. Click on the volumes tab if it is not automatically selected.

5. Select the IASP volumes. Using shift+click or ctrl+click enables the selection of multiple consecutive or additional volumes.

6. Click on Actions → Map to Host or Host Cluster …

7. Select the host in the storage that represents the target IBM i, and click next.

8. Click Map Volumes.

Enabling PowerHA Management of Policy-Based Replication

While the source volumes have not changed, because the target is replicating to new volumes, it is necessary to locate the new volume IDs for the target copy description.

1. Locate the new virtual disk ranges on the target storage.

2. Use the CHGSVCCPYD command to specify new virtual disk ranges for the target copy description.

3. A session in PowerHA describes the relationship between copy descriptions, including the type of replication and is used to manage and control replication. A session can be started in this example using the following command: STRSVCSSN SSN(MYSSN) TYPE(*GLOBALMIR) CRG(MYCRG) DETACHMODE(*ACTIVE)

This command specifies to start a session called MYSSN that is of type Global Mirror. PowerHA uses Global Mirror to represent asynchronous replication as is used with asynchronous policy-based replication. In addition, the command specifies that this session references the CRG named MYCRG. PowerHA automatically pulls together the CRG information and Copy Description information from the copy descriptions that describe sites in the CRG.

The parameter detach mode (DETACHMODE) with a value of *ACTIVE indicates that when the *DETACH operation in PowerHA is performed, the storage will continue replication to the storage in the background. While the data on the copy of the IASP that is accessible on the target node is still a point-in-time copy from when the detach was issued, the target storage controller continues to receive updates from the production storage controller, improving the recovery point and reducing the time required for re-synchronization after a reattach. Using *ACTIVE for detach mode protects the recovery point but uses more storage space on the target storage controller. If you have enough storage, it is recommended to use a detach mode of *ACTIVE.

Results

PowerHA management of Asynchronous Policy-based replication is now configured between the nodes in the CRG. To verify and monitor the status of replication, use one of the following:

• The Display SVC Session (DSPSVCSSN) command. For example, DSPSVCSSN SSN(MYSSN).

• The PowerHA web interface.

• The SQL Service table function QHASM.SESSION_INFO.