I've searched around here on SX and other places but have not found an approach that gives me any traction on my issue. I've a volume (used by Time Machine as it happens) on an external Firewire drive. When the drive is connected, it has 3 volumes. Two out of three eject with no problems but the last one (LaCie) can never be unmounted unless by force (e.g. $ umount -f LaCie). I can see the drive being accessed almost continuously but I have no idea which process is doing this; and lsof is of limited help. Mostly it returns no results as below but occasionally it reports that Finder has a directory open on the volume. But I don't see why that would be a problem as Finder should close any open files or directories when a volume is unmounted. This problem only arose after I upgraded to Mountain Lion. I use a cloning tool (SuperDuper!) but have made sure that is not running; and lsof appears to confirm this. How else can I find out what is locking up the volume? I'm not keen on forcibly ejecting the volume every time I want to disconnect the drive as I surely risk data loss on my main backup disk.

~ $ sudo diskutil unmount /Volumes/LaCie/ 
Volume LaCie on disk1s1 failed to unmount 
~ $ lsof | grep LaCie
~ $ lsof | grep /Volumes/LaCie
~ $
  • Update: the underlying problem persists, namely that I can rarely disconnect the volume without forcing an unmount. In Mountain Lion, TM backups do not work any more without spotlight indexing, so Apple tell us. But despite several days of indexing time, Spotlight still hasn't finished indexing the external drive :-(
    – fairflow
    Sep 30, 2013 at 16:15

1 Answer 1


If you run lsof without sudo, it can only see what files your processes have open, not those open by system or other users. Use sudo lsof | grep /Volumes/LaCie to get a better idea what's going on.

  • Perfect. It was Spotlight. Ran into the mdworker[79696]: Unable to talk to lsboxd issue. Applying the fixes documented here and elsewhere (restart in Safe Mode and restart again) has made my volume ejectable again.
    – fairflow
    Sep 28, 2013 at 15:20
  • Are you running an older version of OS X? My impression was that the Unable to talk to lsboxd issue appeared in 10.8.2, and got progressively fixed in 10.8.3 and .4. Sep 28, 2013 at 16:24
  • 10.8.5 and I'm not the only one to have issues of this kind...but I didn't do a clean install, enough to do already!
    – fairflow
    Sep 29, 2013 at 9:06
  • Ah, so it's possible there was a messed-up cache (or whatever the actual problem was -- I never saw a full diagnosis) left over from 10.8.2. Sep 29, 2013 at 13:44
  • 1
    In Ask Different: lsof without sudo may not list all open files Jan 30, 2014 at 8:01

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