A phased upgrade upgrades a portion of the nodes in the cluster at a time. The advantage of this method is that it requires lesser server downtime than a full upgrade.
Depending on the size of the cluster, you can split it into two or more subclusters and upgrade each subcluster separately. Performing a phased upgrade is similar to doing a full upgrade multiple times, so a phased upgrade supports all upgrade paths that are supported by a full upgrade.
Symantec provides both a script-based and a web-based installer to perform a phased upgrade of Storage Foundation and High Availability (SFHA). Before you start the upgrade, confirm that you have licenses for all the nodes that you plan to upgrade.
There is some downtime involved during this upgrade. However, you can review the procedures and carefully plan out the movement of the service groups from node-to-node to minimize the downtime for any particular service group. Downtime exists from the time you prepare the second subcluster until you finish activating the first subcluster. You can do the following to minimize the downtime:
- Split the cluster into two subclusters of equal or near equal size.
- Split the cluster so that your high priority service groups remain online during the upgrade of the first subcluster.
- Before you start the upgrade, back up the Symantec Cluster Server (VCS) configuration files, main.cf and types.cf, which are located in the /etc/VRTSvcs/conf/config/ directory.
Performing a phased upgrade involves the following steps:
- Moving the service groups to the second subcluster
- Upgrading the operating system on the first subcluster
- Upgrading the first subcluster
- Preparing the second subcluster
- Activating the first subcluster
- Upgrading the operating system on the second subcluster
- Upgrading the second subcluster
- Finishing the phased upgrade
You can perform a phased upgrade from SFHA 5.1 or other supported previous versions to SFHA 6.1.
During a phased upgrade, note that:
- VCS and the service groups cannot stay online on the second subcluster while it is being upgraded.
- Do not add, remove, or change resources or service groups on any nodes during the upgrade. These changes are likely to get lost after the upgrade.
- You need to perform the operations between upgrading subclusters manually. The entire upgrade procedure cannot be performed through the script-based or the web-based installer.
Symantec Storage Foundation and High Availability documentation for other releases and platforms can be found on the SORT website.
