Planning an Upgrade

Before you upgrade your system, back it up. Make backup copies of all existing disk-stores, server-side code, configuration files, and data across the entire cluster. To get a backup of the data that includes the most recent changes may require that traffic across the cluster is stopped before the backup is made. The discussion at Creating Backups for System Recovery and Operational Management explains the process, and the backup disk-store command reference page describes how to use the gfsh backup disk-store command to make a backup.

Guidelines for Upgrading

Schedule your upgrade during a period of low user activity for your system and network.
Verify that the machines hosting the cluster members meet the Host Machine Requirements of the upgraded cluster.
Important: After all locators have been upgraded, do not start or restart any processes that use the older version of the software. The older process will either not be allowed to join the distributed system or, if allowed to join, can potentially cause a deadlock.
Verify that all members that you wish to upgrade are members of the same distributed system cluster. A list of cluster members will be output with the gfsh command:
```
gfsh>list members
```
Locate a copy of your system’s startup script, if your site has one (most do). The startup script can be a handy reference for restarting upgraded locators and servers with the same gfsh command lines that were used in your current installation.
Identify how your current cluster configuration was specified. The way in which your cluster configuration was created determines which commands you use to save and restore that cluster configuration during the upgrade procedure. There are two possibilites:
- With gfsh commands, relying on the underlying cluster configuration service to record the configuration: see Exporting and Importing Cluster Configurations.
- With XML properties specified through the Java API or configuration files: see Deploying Configuration Files without the Cluster Configuration Service.
Do not modify region attributes or data, either via gfsh or cache.xml configuration, during the upgrade process.

Version Compatibilities

Your choice of upgrade procedure depends, in part, on the versions of VMware GemFire involved.

For best reliability and performance, all server components of a GemFire system should run the same version of the software. For the purposes of a rolling upgrade, you can have peers or cache servers running different minor versions of VMware GemFire at the same time, as long as the major version is the same. For example, some components can continue to run under version 9.10 while you are in the process of upgrading to version 9.15.

Upgrade to the Latest Version 9 from an Earlier Version 9

If possible, follow the Rolling Upgrade procedure. A multi-site installation can also do rolling upgrades within each site. If a rolling upgrade is not possible, follow the Off-Line Upgrade procedure. A rolling upgrade is not possible for a cluster that has partitioned regions without redundancy. Without the redundancy, region entries will be lost when individual servers are taken out of the cluster during a rolling upgrade.

Java Notes

To check your current Java version, type java -version at a command-line prompt.
VMware GemFire 9.x requires Java SE 8, version 272 or a more recent version.
The VMware GemFire product download does not include Java. You must download and install a supported JRE or JDK on each system running GemFire. To obtain best performance with commands such as gfsh status and gfsh stop, install a full JDK (not just a JRE).