I recently installed Mac OS 10.10 (Yosemite) onto an external USB drive. It has been working fine for the past few days. When I need to switch OS installs, I shut down the computer and then pull out the drive. However I think I just pulled out the drive a little too early, while it was still being written to, and now the drive is not being recognized at all by the computer. I get the following message.

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Is there any way I can still save the drive without losing all my work on it? Thanks.

  • If you have anything not that drive that you really need to recover do not initialize it and I'd use DiskWarrior to attempt recovery. I'd also make a binary backup if the USB drive using dd before doing anything. – user3439894 Jul 14 '15 at 17:20

You could plug it in, hit "Ignore", open "Disk Utility", and attempt to "Repair" the disk. Otherwise, try to initialize the disk and copy the folder contents.

P.S. Just as a side note, I would recommend using an external hard drive(SSD or HDD) to run OS X, since it would operate a little faster.

  • your PS… you mean internal? – Tetsujin Jul 14 '15 at 15:01
  • @Tetsujin No, I mean the one he has Yosemite installed on. The corrupt one. – SentientBacon Jul 14 '15 at 15:40
  • What do you mean be "initialize the disk and copy the folder contents"? Right now i care more about the files and would like to safely get them back rather then trying to fix the actual OS on the drive. – Acoop Jul 14 '15 at 16:26
  • Additionally, I specifically got a high end USB- 3 with read speeds of 250 MBs and the OS runs pretty fast. Not as fast as my internal SSD, but only slightly noticeably different. – Acoop Jul 14 '15 at 16:27
  • Ok, thats what I expected. It's just that when I tried it, it failed miserably. But that's just because I have an old Mac. – SentientBacon Jul 14 '15 at 16:29

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