I store some sensitive data on encrypted disk images. Sometimes for convenience I mount one of these disk image files (.dmg) over the LAN and occasionally forget to unmount it.

A problem arises where even if the client machine where it's mounted is put to sleep, the host still sees the disk image as being in use and will return the error:

The following disk images couldn't be opened
Reason: Resource temporarily unavailable

To gain access to the image I need to physically find which computer it's mounted on, wake it from sleep and eject the image.

How can I force unmount an image which is mounted by a network client?

  • Can you use sudo umount -f <mountpoint>?
    – ecnepsnai
    Jun 11, 2016 at 22:58
  • the volume is not mounted on the host so there is no mountpoint Jun 11, 2016 at 23:39
  • Need more information - where are the DMG files stored ? Are they on a network share or are they on a server or a network connected USB ? Is it a Windows or OS X system ? Jun 12, 2016 at 4:32
  • @Danijel-JamesW - Both machines are running OS X. The DMG is on a drive mounted on the host machine. Jun 12, 2016 at 14:21
  • Can you check to see if the file is locked? (Get Info on the .dmg)
    – Allan
    Jun 14, 2016 at 14:32


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