umount: unmount(/Volumes/your disk name): Resource busy

turns out os x has no ‘fuser’ command. oh well. But

umount -f /your/device/path

does the trick in many cases where the pansy finder rejects to eject (aka unmount) a volume

6 Responses to “umount: unmount(/Volumes/your disk name): Resource busy”

  1. Anonymous Says:

    Try “lsof | grep /your/device/path” to see what’s using the device.

  2. Scott Perry Says:

    frequently lsof shows no processes with file handles in the mountpoint, but umount still will fail.
    this is most often indicative of a faulty USB-IDE adaptor or a dropped/failed device.

  3. Curt Says:

    Thanks for posting this, I have this problem every day at work with a crappy shared drive at Rackspace.

  4. Simon Says:

    Try diskutil umount /path/to/drive, it worked even without the “force” option. (see comments at http://loopkid.net/articles/2008/06/27/force-unmount-on-mac-os-x). I have no idea however about why this works and umount doesn’t… :P

  5. Donald E. Payne Says:

    I had same problem with “device busy”. One time both “lsof” and “fuser” reported no files open; another time “lsof” showed a process with a file open. (my MacOS X, 10.5.2 has both, and both appear to automatically check for open files anywhere in a given file system):
    $ userid root lsof ‘/Volumes/2ndHardrive 1′
    COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
    fseventsd 76 root 8u REG 14,5 0 1892050 /Volumes/2ndHardrive 1/.fseventsd/000000000038f4c5

    fseventsd is a daemon that watches for changes to a mounted volume, for the benefit of applications like Finder and Spotlight. It keeps a file open on the volume, so it is “busy”.

    Then I read here
    http://lists.apple.com/archives/Darwin-dev/2008/Sep/msg00039.html
    that you are not supposed to use the direct command-line tools like “mount” and “umount” on MacOS, and that “DA [Disk Arbitrator] will notify fseventsd to stop looking”. Surprising to me — I thought MacOS X was basically UNIX.

    DA appears to be either a GUI or an API. I want a command line. So I found, via “man -k disk”, the commands “disktool” (deprecated) and “diskutil” as mentioned above. diskutil works when umount fails; I guess it first tells fseventsd to stop looking.

  6. David Says:

    Discovered after dealing with a frustrating bout with this software that yes, indeed, the ubiquitous CleanMyMac software can create this problem. It has a cache monitoring system whenever a new device is connected, supposedly to “clean” out the trash in these drives; but it also makes a drive unmountable, as it keeps on monitoring the drive.

    The second I removed the application I was able to create the 10.9 USB installer.

    It took me much troubleshooting to discover this; and as convenient as it is to utilize this all-in-one utility, this one reason makes it a nobrainer for me. It uninstalled itself. Sighhhhh.

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