Q: Why does my external USB drive randomly disappears, unmounts, ejects itself
Hello,
I've seen this problem posted under different headlines but I thought I'll post it here under a clearer headline, and hopefully, a better description.
When plugging a brand new external USB drive into my MacBook Air (formatted and prepared by Apple's Disk Utility), OSX seems to unexpectedly unmount it a few minutes later. I've been having this issue with an older external drive, I thought there was something wrong with the drive itself so I bought a new external USB drive (different brand) and copied all the data over (TimeMachine files), but surprisingly the problem presisted.
As I mentioned, I use the external drive for my TimeMachine, and every few minutes or so, the drive disappears from the desktop and an error pops up saying:
"The disk was not ejected properly. If
possible, always eject a disk before
unplugging it or turning it off.
To eject a disk, select it in the Finder and choose File
> Eject. The next time you connect the disk, Mac OS
X will attempt to repair any damage to the
information on the disk."
The only way to mount it again is to turn the drive off an on again. Unpluging the USB cable for a couple of minutes then plug it back again won't do. It even becomes unavailable in Disk Utility (when pluggen in of course).
I tried plugging the USB drive directly into my MacBook Air, into my Thunderbolt display through USB, and into my external USB hub. All with the exact same symptoms.
NOTE: Although this problem seems to be common on OSX, I'm not sure, if in my case, it's related to the fact that I use the software PKard, which allows OSX to accept Government CAC cards (otherwise known as SmartCards).
Computer: MacBook Air 13-inch, Mid 2011
OS: Mac OS X 10.8.4 (12E55)
Memory: 4 GB DDR3
External Display: 27" Thunderbolt display
Eternal USB devices: SCR331 Card Reader; USB SATA drive enclosure (plugged into display); 4-port USB hub.
MacBook Air, OS X Mountain Lion (10.8.4)
Posted on Jul 3, 2013 10:36 AM