Performing a CRG planned Global Mirror switchover

This scenario shows what takes place in a HyperSwap environment with Global Mirror when a planned Global Mirror switchover takes place

Before you begin

This scenario uses the configuration created in the Configure HyperSwap with Global Mirror using Copy Services Manager (CSM). Review this configuration before proceeding with the switchover operation.

A restriction for the Global Mirror switchover is that the Global Mirror link must be active at the time of the switchover.

About this task

In this scenario, the IBM i system, NODE_1 is the primary node of the PowerHA environment and the data on DS8000 A, stored in IASP_1, is configured for Global Mirror. It replicates data from the primary DS8000 A to a DR site with DS8000 C and a separate IBM i system, NODE_2. In addition to a Global Mirror connection, DS8000 A has a HyperSwap relationship to DS8000 B. Both storage units are attached to NODE_1. All disk units in the IASP on DS8000 A correspond to disk units in DS8000 B and are linked across a synchronous connection.

Here, a Global Mirror switchover is planned and performed from the primary IBM i system, NODE_1 to the IBM i system, NODE_2. Both the Global Mirror and HyperSwap connections begin with the same primary DS8000.

Procedure

The diagrams below depict the stages of a CRG switchover in an HyperSwap environment with Global Mirror replication.

1. Begin with the environment in normal operation as described above.

2. Type in the following command to initiate the Global Mirror switchover from the IBM i NODE_1 system to the NODE_2 system in the cluster.

   CHGCRGPRI CLUSTER(PWRHA_CLU) CRG(HYSGMIRCRG)

   This indicates to PowerHA that the user wants to change the primary node in the cluster resource group. In the scenario provided, this changes the direction of the Global Mirror, changing the primary DS8000 from DS8000 A to DS8000 B and the primary system from NODE_1 to NODE_2.

3. The command switches the primary system from IBM i production system with DS8000 A to the NODE_2 system and DS8000 C. The Global Mirror configuration will replicate in the opposite direction after it is started.

4. As the Global Mirror configuration reversed from DS8000 C to DS8000 A, the HyperSwap replication connection from DS8000 A to DS8000 B changes the from a synchronous to an asynchronous connection because it now exists at the target side of the Global Mirror.

Result

The switchover should complete successfully. Notice the primary has changed and the Global Mirror is replicating in the opposite direction.

Example

Figure 1. Changing the CRG primary in a CRG switchover within a HyperSwap with Global Mirror configuration

Open