Fault Tolerance of the Group Server

The group server is automatically fault-tolerant, if and only if the primary realm server has a backup server.

The group server runs inside the primary realm server and its backup server. That is, the group server does not run in satellites nor in their backups. Each realm server automatically determines whether it can and should run an embedded group server, based on the realm configuration, and on the server’s role (see Affiliated Realm Servers).

Group servers within a primary realm server and its backup server automatically coordinate for fault-tolerant operation. Group members automatically failover between these two servers.

Note: Group members that failover to a secondary group server within a backup realm server process remain with that group server until it fails. In contrast, clients that have migrated to a backup realm server automatically return to the regular realm server when it again becomes available.

This can result in a situation where clients depend on regular server A for realm information, but as group members they depend on backup server B to coordinate groups. Although this divergence might seem counterintuitive, it is the expected behavior.

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