Wednesday, December 23, 2009

XenServer - There was an error while attempting to unmount the NFS share

Recently in XenServer I was attempting to remove an ISO Library (CIFS) that I had created that no longer existed. All attempts using Destroy, Forget, Detach from XenCenter failed with error "There was an error while attempting to unmoun the NFS Share".

At this point I went to one of the hosts consoles and typed xe sr-list name-label="name of iso directory". This returned the uuid of the SR (which isn't listed in the GUI). From here I was able to run xe sr-destroy uuid=thesr'suuid. This returned "The SR is still connected to a host via a PBD. It cannot be destroyed."

Okay, what hosts and pbd's have it locked?

xe pbd-list sr-uuid=1c5a224d-f265-c84f-8e7d-8f4f891559c1. This returned that each host had a pbd to it... Taking note of each hosts pbd uuid I ran xe pbd-unplug uuid=xxxxxx for each uuid that displayed "currently-attached (RO): true. Each one unplugged successfully except one which returned "error code: SR_Backend_Failure_74 Error parameters: , NFS unmount error [opterr=error is 255],". This told me at least which host was at fault since the pbd uuid is listed directly above the host uuid ( xe host-list host-uuid=xxxxxxxx).

At this point a reboot of the host that was at fault cleared up the issue and I was able to forget the Library


  1. Odd, but the solution is fitting given the name of your blog ;)

  2. Had the same issue a reboot was required, weird because i managed to unmount it fine on another machine, another little quirk found in xenserver