Nfs – monitoring nfs with monit

monitnfs

I'd like to monitor NFS mounts and the NFS server process using Monit.

On the server, I'd need a PID file, but I can't seem to find a way of getting that created with existing configuration files. Is there a way to do this, or has anyone monitored the server in a different way (checking if port 53 is active, etc).

On clients, I was thinking of making Monit simply look for a specific file in an NFS mount, and if it's accessible, all is well. Problem is, if the NFS server does go down, file requests usually hang (perhaps even indefinitely, not sure). How would one get around this issue with monit?

Any configuration examples would be greatly appreciated!

Best Answer

As for the "hanging" of the Monit process during NFS server faults, this can be circumvented by two methods.

  1. You change the NFS mount options from hard to soft, which causes the NFS layer to issue an I/O error to the accessing application after retrans retries. As this can introduce other problems with respect to data integrity (your writing applications need to be able to cope with I/O errors or at least exit cleanly, without corrupting the file written), you may also try to:
  2. asynchronize your check (disentangle it) from Monit. You may define a cronjob regularly checking your NFS-mounted file and writing another "NFS state file" eg. to /tmp. That way, just the cronjob will hang (and not your Monit client) if the NFS server goes away. Your Monit check now just checks this second-stage "NFS status file" AND whether it is much older than the cronjob's frequency (which would indicate such hanging of NFS).

Hope this helps!

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