SAP Landscape Management 3.0, Enterprise Edition

Performing a Forced System Replication Takeover

If your primary system is not available, due to a disaster or planned downtime for example, and you have decided to fail over to the secondary system, you can perform a forced system replication takeover on your secondary node.

Prerequisites

  • You have permission Service(ForcedPrepare,ForcedUnPrepare,ForcedStart,ForcedStop).

    For more information, see Standard Permissions.

  • You have assigned the roles and groups required to perform the operation.

    For more information, see Standard Roles and Groups.

  • You have set up and configured system replication.

    For more information, see Setting Up System Replication.

  • SAP Host Agent 7.20 SP 191 or above

  • You have selected the Show Advanced Shutdown Options when Stopping Operations checkbox during engine configuration.

    For more information, see Configuring Advanced Operation Settings.

  • The secondary system is independently up and running.

  • You have assigned the client connect address for the automatic IP redirect during system replication takeover.

    For more information, see Instance Properties.

Context

A forced system replication takeover implements the SAP HANA hdbnsutil -sr_takeover operation. Use the forced system replication takeover operation only in case of emergency operations with support of a cluster for the client connect IPs or within a custom process, where other steps ensure the avoidances of a network split, a so called“split brain” as well as the client connectivity.

  • If site B (secondary tier) is taking over, the operation will not make any attempt to stop or change the state of site A (primary tier). It depends on the data center infrastructure and the exception causing the takeover, how site A can be made unavailable for clients to avoid a "split brain."

  • You are responsible to only do a forced system replication takeover if all transactions executed on site A have been replicated to site B, and site A has been made unavailable for clients. For example, make sure the primary tier on site A is completely stopped or re-assign the virtual IP to the host assigned to site A.

  • Since multiple ways of backups are supported, do not start site A as primary tier in case there are possibilities for site A to share backups with site B. If and how backups are synced is in the responsibility of the administrators.

Procedure

  1. Choose Operations.
  2. Choose Systems from the tabs.
  3. From the Operations dropdown for the secondary system, choose Start of the navigation pathSAP HANA Replication Next navigation step Forced System Replication TakeoverEnd of the navigation path.
  4. Optional: Select the Set Note checkbox and enter a note to be displayed in the Description column of the instance.
  5. Choose Execute.

    On the Configuration screen, SAP Landscape Management displays two primary systems.

    The former secondary, now the new primary is in status Running.

Next Steps

  1. Optional: Register the former primary system as the secondary system when it becomes available again.

    For more information, see Registering a Secondary Tier for System Replication.

  2. Optional: Execute the Failback.

    For more information, see Performing a Failback.

Monitoring System Replication