I had again some troubles with my XSan. I have 1 MDC (client/controller) and 2 clients and 2 Volumes on the XRaid. All clients and all volumes automounted as expected, except one volume on one of the clients 
I saw the client in the list for that particular volume in the XSan Admin application, but when i hit “mount read and write” the status of that client shows “mounting” for a short time and then “unmounted”. No luck until today.
The problem is easy to solve, but anyoing to find:
I started Terminal and browsed to the /Volumes directory. There was the folder for the troublesome XSan volume and at the second sight i found out, that the folder is not empty! That caused XSan admin to mount without any luck. The cause for the folder not being empty was a folder called “Qmaster_Cluster_Storage”. And now i knew what went wrong 
I have a QMaster cluster set up on this server as well and have the cluster storage set to a directory on one of the XSan volumes. Maybe sometime the server restarted without the XSan volume mounted and QMaster created the (now) missing cluster storage folder. After deleting the /Volumes/<name of my Xsan volume> folder i could successfully mount the volume for this client in XSan Admin.
Easy to solve, but a pain in the ass
3 comments
Raihan Hasnain Rahman says:
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Thanks dude, you saved my ass too
wolfgang.reutz says:
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glad this was helpful for others, i have to do this quiete often because it seems that qmaster starts faster than the xsan volumes being mounted when starting the system.
Daniel says:
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That’s it! Thanks! Spent 2 hours this morning trying to track down the issue. Thanks for the fix!