Upgrading Tungsten Cluster
To upgrade an existing installation of Tungsten Cluster, the new distribution must be downloaded and unpacked, and the included tpm
command used to update the installation. The upgrade process implies a small period of downtime for the cluster as the updated versions of the tools are
restarted, however the process that takes place should not present as an outage to your applications providing steps when upgrading the connectors
are followed carefully. Any downtime is deliberately kept to a minimum, and the cluster should be in the same operational state once the upgrade has finished as
it was when the upgrade was started.
During the update process, the cluster will be in MAINTENANCE mode. This is intentional to prevent unwanted failovers during the process, however it is important to understand that should the primary fail for genuine reasons NOT associated with the upgrade, then failover will also not happen at that time.
It is important to ensure clusters are returned to the AUTOMATIC state as soon as all Maintenance operations are complete and the cluster is stable.
Rolling upgrades of the Tungsten software is not supported unless specifically guided by Continuent Support. Doing so can cause miscommunication between components running older/newer versions of the software that may prevent switches/failovers from occurring, therefore it is recommended to upgrade all nodes in place. The process of the upgrade places the cluster into MAINTENANCE mode which in itself avoids outages whilst components are restarted, and allows for a successful upgrade.
From version 7.1.0 onwards, the JGroup libraries were upgraded, this means that when upgrading to any release to 7.1.0 onwards FROM any release OLDER than 7.1.0 (for example 6.1.0 -> 7.1.4), all nodes must be upgraded before full cluster communication will be restored. For that reason upgrades to 7.1.0 onwards from an OLDER release MUST be performed together, ensuring the cluster is only running with a mix of manager versions for as little time as possible. When upgrading nodes, do NOT SHUN the node otherwise you will not be able to recover the node into the cluster until all nodes are upgraded, which could result in an outage to your applications.
Additionally, do NOT perform a switch until all nodes are upgraded. This means you should upgrade the primary node in situ. Providing the cluster is in MAINTENANCE, this will not cause an outage and the cluster can still be upgraded with no visible outage to your applications.