Checking Member Versions in a Mixed Cluster

During a rolling upgrade, you can check the current GemFire version of all members in the cluster by looking at the server or locator logs.

When an upgraded member reconnects to the distributed system, it logs all the members it can see as well as the GemFire version of those members. For example, an upgraded locator will now detect GemFire members running the older version of GemFire (in this case, the version being upgraded-- GFE 8.0.0) :

[info 2013/06/03 10:03:29.206 PDT frodo <vm_1_thr_1_frodo> tid=0x1a]  DistributionManager frodo(locator1:21869:locator)<v16>:28242 started on frodo[15001]. There
        were 2 other DMs. others: [frodo(server2:21617)<v4>:14973( version:GFE 8.0.0 ), frodo(server1:21069)<v1>:60929( version:GFE 8.0.0 )] (locator)

After some members have been upgraded, non-upgraded members will log the following message when they receive a new membership view:

Membership: received new view [frodo(locator1:20786)<v0>:32240|4]
          [frodo(locator1:20786)<v0>:32240/51878, frodo(server1:21069)<v1>:60929/46949,
          frodo(server2:21617)<v4>( version:UNKNOWN[ordinal=23] ):14973/33919]

Non-upgraded members identify members that have been upgraded to the next version with version: UNKNOWN.