In an Active/Standby configuration, the backup server is not actively running the PostgreSQL, but stands by in case the primary server experiences a failure. In an Active/Active configuration, each server is actively running a PostgreSQL instance, while acting as a backup for the other server in case of failure. The following list provides requirements that should be adhered to when protecting a PostgreSQL resource instance in an active/standby or active/active configuration.
- The PostgreSQL DataDir and Write-Ahead-LogPath (PGDATA/pg_xlog) must be installed on one or more shared file systems. The paths DataDir and WAL-Path must be shared between all servers that will protect the resource instance.
• The PostgreSQL Operating System User must own the data directory and directory containing the Write-Ahead-LogPath.
• The PostgreSQL database must have been created using the utility initdb. The initdb utility must be run as the PostgreSQL owner using the –D <datadir> option.
• The automatic startup of the default PostgreSQL instance must either be disabled or the default PostgreSQL instance must be restricted to running on a port other than those intended for use with LifeKeeper.
• The automatic startup of the PostgreSQL instance to be protected by LifeKeeper must be disabled. LifeKeeper will control the starting and stopping of the protected instance.
• The PostgreSQL instance must be started manually prior to hierarchy creation. It is required that the instance be started with the backend option –o “–p <port>” specified to the pg_ctl utility.
- The StartupLogPath, SocketPath and the ExecutablePath can be installed to optional shared file systems on the primary server or each local node file system.
• The PostgreSQL Operating System User must own the directory containing the socket path.
• The PostgreSQL Operating System User must have write permissions on the directory containing the StartupLogPath.
- It is recommended that each instance use a unique port and socket path when running multiple instances in either an Active/Standby or Active/Active scenario.
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