HP ServiceGuard will not run unless all the nodes use the same version of the software. The program cmcheckconf will return an error something like this:

Checking nodes ... Done
Checking existing configuration ... Done
This node is at revision A.11.17.01 of Serviceguard, node cluster2 is at A.11.18.00.
Unable to make configuration changes when a node in the cluster is at a different revision.

It is apparently possible (but not recommended) to run a different version of HP-UX on different nodes. However, this requires that the same version of the JFS filesystem (vxfs) is installed everywhere, and any application libraries that are needed must be installed – and the JFS upgrade may require a new licensing fee.

The recommended path is to run the same version of HP-UX on every system in the cluster, and requires the same version of ServiceGuard on every system in the cluster. The application itself should also be the same version, but if properly written may allow “rolling upgrades” – that is, one system has a different version than the next. A rolling upgrade allows you to keep the system going and responding even during the upgrade.

In summary:

  • Different versions of HP-UX: not recommended (difficult and costly to get right)
  • Different versions of ServiceGuard: no
  • Different versions of application: yes (if written correctly)