Upgrading Cluster Functionality

The rolling upgrade feature allows you to upgrade the version of VxVM running in a cluster without shutting down the entire cluster. To install the new version of VxVM running on a cluster, make one node leave the cluster, upgrade it, and then join it back into the cluster. This operation is repeated for each node in the cluster.

Each Volume Manager release starting with Release 3.1 has a cluster protocol version number associated with it. The cluster protocol version is not the same as the release number or the disk group version number. The cluster protocol version is stored in the /etc/vx/volboot file. During a new installation of VxVM, the vxdctl init command creates the volboot file and sets the cluster protocol version to the highest supported version.

Each new Volume Manager release supports two cluster protocol versions. The lower version number corresponds to a previous Volume Manager release. This has a fixed set of features and communication protocols. The higher version number corresponds to the new release of VxVM which has a new set of these features. If the new release of VxVM does not have any functional or protocol changes, but only bug fixes or minor changes, the cluster protocol version remains unchanged. In this case, the cluster protocol version does not need to be upgraded.

During a rolling upgrade, each node must be shut down and the Volume Manager release with the latest cluster protocol version must be installed. All nodes that have the new release of VxVM continue to use the lower level version. A slave node that has the new cluster protocol version installed tries to join the cluster. If the new cluster protocol version is not in use on the master node, it rejects the join and provides the current cluster protocol version to the slave node. The slave retries the join with the cluster protocol version provided by the master node. If the join fails at this point, the cluster protocol version on the master node is out of range of the protocol versions supported by the joining slave. In such a situation, you must upgrade the remainder of the cluster through each intermediate release of VxVM to reach the latest supported cluster protocol version.

Once you have installed the new release on all nodes, run the vxdctl upgrade command on the master node to switch the cluster to the higher cluster protocol version. See “Upgrading the Cluster Protocol Version” for more information.