Visiting customer sites and engaging in conversations with professionals from different fields is always a great learning experience. During one such visit to an India-based company, I had an interesting conversation with a Windows admin during lunch. He shared an incident where cluster networks were shown as unavailable in Failover Cluster Manager. This sparked my curiosity, and I decided to investigate further.

Upon examining the cluster logs, I came across some interesting messages that shed light on the issue:

========B02===========
00000648.00002464::2016/11/29-08:58:45.173 INFO [FTI][Initiator] This node (1) is initiator
00000648.00002464::2016/11/29-08:58:45.173 WARN [FTI][Initiator] Ignoring duplicate connection: usable route already exists
00000648.00002464::2016/11/29-08:58:45.173 INFO [CHANNEL 147.170.123.251:~3343~] graceful close, status (of previous failure, may not indicate problem) ERROR_SUCCESS(0)
00000648.00002464::2016/11/29-08:58:45.174 WARN cxl::ConnectWorker::operator (): GracefulClose(1226)’ because of ‘channel to remote endpoint 147.170.123.251:~3343~ is closed’

========B01============
00004090.00005db0::2016/11/29-08:58:45.157 INFO [FTI][Follower] This node (2) is not the initiator
00004090.00005db0::2016/11/29-08:58:45.157 DBG [FTI] Stream already exists to node 1: false
00004090.00005db0::2016/11/29-08:58:45.157 DBG [CHANNEL 147.170.123.252:~54783~] Close().
00004090.00005db0::2016/11/29-08:58:45.157 INFO [CHANNEL 147.170.123.252:~54783~] graceful close, status (of previous failure, may not indicate problem) ERROR_SUCCESS(0)
00004090.00005db0::2016/11/29-08:58:45.157 INFO [CORE] Node 2: Clearing cookie 63cfe37d-42be-4211-8cd8-6db6b3344b52
00004090.00005db0::2016/11/29-08:58:45.157 DBG [CHANNEL 147.170.123.252:~54783~] Not closing handle because it is invalid.
00004090.00005db0::2016/11/29-08:58:45.157 WARN mscs::ListenerWorker::operator (): GracefulClose(1226)’ because of ‘channel to remote endpoint 147.170.123.252:~54783~ is closed’

Based on the cluster logs and the highlighted message “Ignoring duplicate connection: usable route already exists,” we can conclude that this issue is caused by stale information on the network from the rejecting node.

Interestingly, the solution to fix this error was to reboot the active node. However, it is worth noting that this issue could also be caused by real network problems or certain antivirus software.

If you encounter a similar issue where cluster networks are shown as unavailable in Failover Cluster Manager, it is recommended to check the cluster logs for any relevant messages. If the “Ignoring duplicate connection” message is not present, further investigation may be required.

Have you ever encountered this issue? If so, please share your solution in the comments below.