Recovery options for Passive replica configurations

If one or both parts of the IBM Storage Scale Primary with attached IBM Storage Scale Passive configuration are lost, you have several recovery options to consider.

Situation: Planned loss of the IBM Storage Scale Primary instance

If the IBM Storage Scale Primary instance is being taken offline due to a planned outage, such as regular maintenance, the administrator typically performs the following general failover steps:
  1. Run the Prepare Primary for Takeover operation on the active Primary instance. This operation causes the nodes of the Primary instance to shut down and detaches the shared volumes from the Primary instance.
  2. In the Block Storage Replication page of the console for the IBM Storage Scale Primary instance, select the replication instance, and for each shared volume pair, perform the Failover operation. As part of this operation the administrator can choose to switch roles and enable replication in the reverse direction, or simply disable replication after the failover completes. If you disable the replication, the primary instance cannot be reused. You must create a new passive instance.

Situation: Unplanned loss of the IBM Storage Scale Primary instance

In this scenario, when you perform a failover operation from the passive rack, the original block storage replication is deleted. The GPFS passive instance becomes the new primary instance. If you need to have an active-passive topology, you must create a new block storage replication entry between the volumes used by the new primary instance and the volumes in the new passive rack, then create a GPFS passive instance, and associate this passive instance with the new primary instance.

If the IBM Storage Scale Primary instance becomes unavailable due to an unplanned outage, the administrator typically performs the following failover steps:
  1. In the Block Storage Replication page of the console for the IBM Storage Scale Passive instance, select the replication instance, and for each shared volume pair, perform the Failover operation. As part of this operation the administrator selects to perform an unplanned failover operation.
  2. From the console of the system where the Passive instance is located, open the Manage > Operations page of the Instance Console for the Passive instance, and run the Passive Takeover operation.

Situation: Loss of the IBM Storage Scale Passive instance

In the unlikely event that the IBM Storage Scale Passive instance is lost, you can reconnect a new Passive instance:
  1. Deploy a new Passive instance, creating the necessary file systems and storage volumes as needed to match the Primary configuration instance.
  2. Attach the Passive configuration to the Primary configuration by using the Add New Member operation. As part of this operation, provide the Manager IP address for the Passive configuration instance.