Restrictions for multiple standby databases

There are a number of restrictions that you should be aware of if you are planning to deploy multiple HADR standby databases.

Important: Multiple standby with Pacemaker is not available in version 11.5.4. Support for multiple standbys has been added for version 11.5.5 and later.

The restrictions are as follows:

  • You can have a maximum of three standby databases: one principal standby and up to two auxiliary standbys. The exception is for Db2 pureScale environments, in which you can only have one standby (the principal standby).
  • Only the principal standby supports all the HADR synchronization modes; all auxiliary standbys will be in SUPERASYNC mode.
  • IBM Tivoli System Automation for Multiplatforms (SA MP) and Pacemaker support apply only between the primary HADR database and its principal standby. The exception is for Db2 pureScale environments, in which SA MP only manages the local cluster and does not automate failover to the standby cluster. Pacemaker automation with pureScale HADR is not supported.
  • The hadr_target_list database configuration parameter must be set on all the databases in the multiple standby setup. Each standby must include the primary in its hadr_target_list setting.