About rolling upgrades


About rolling upgrades
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The rolling upgrade minimizes downtime for highly available clusters to the amount of time that it takes to perform a service group failover. The rolling upgrade has two main phases where the installer upgrades kernel packages in phase 1 and VCS agent packages in phase 2.

Note:

You need to perform a rolling upgrade on a completely configured cluster.

The following is an overview of the flow for a rolling upgrade:

The installer performs prechecks on the cluster.

The installer moves service groups to free nodes for the first phase of the upgrade as is needed.

Application downtime occurs during the first phase as the installer moves service groups to free nodes for the upgrade. The only downtime that is incurred is the normal time required for the service group to fail over. The downtime is limited to the applications that are failed over and not the entire cluster.

The installer performs the second phase of the upgrade on all of the nodes in the cluster. The second phase of the upgrade includes downtime of the Veritas Cluster Server (VCS) engine HAD, but does not include application downtime.

Figure: Example of the installer performing a rolling upgrade illustrates an example of the installer performing a rolling upgrade for three service groups on a two node cluster.

Figure: Example of the installer performing a rolling upgrade

The following limitations apply to rolling upgrades:

Rolling upgrades are not compatible with phased upgrades. Do not mix rolling upgrades and phased upgrades.
You can perform a rolling upgrade from 5.1 and later versions.

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