Possible Duplicate:
Disable “the disk was not ejected properly” message

When I have a USB Device like a SD Card, USB Drive or external hard drive, I always need to unmount it, otherwise OS X complains about the device not being ejected properly.

On Windows, the solution to this is trivial: Disable the File System Cache for USB Drives, so that they can be immediately and safely removed.

Does OS X have a way to disable the cache?

  • 2
    FWIW, the supposed dupe is absolutely not an exact duplicate. This question is about disabling the write cache so that the the device can be safely removed; the other is about simply turning off the message and ignoring the risk.
    – Reid
    May 5, 2011 at 20:03
  • 1
    Please reopen this question. It's not a duplicate.
    – nalply
    Dec 24, 2011 at 12:26
  • Agreed, not a duplicate for the reasons @Reid mentions. I found this post searching for "os x disable write cache".
    – Johann
    Oct 20, 2014 at 15:38
  • i think it's safe to say osx does not have this feature. osx does so much work behind the scenes that we have a hard time limiting it even on mounted volumes.....but is there a way to mount outside of finder -- with some kind of ftp/web interface accessing it as /disk1s2? Oct 20, 2014 at 16:16

1 Answer 1


On SuperUser Q&A another user asked a similar question. The solution is a little bit tricky/efforty:

This should be possible by manually mounting the drive via the terminal. You'll have to eject the drive when you plug it in and then remount it in the terminal using the noasync option.

The best way to go about this would be to run mount in the terminal and take down the device so you know what to remount. Then umount /dev/disk1s1 (where disk1s1 is the device name) then mount -o noasync /dev/disk1s1. This method would also apply to most linux distros.

As you can see, it's easier to just remember to eject.

  • Use fstab to automate this process!
    – Joy Jin
    Oct 29, 2020 at 0:36

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