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Old 11-27-2011, 05:54 PM   #1
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Trying to erase my external hard drive with disk utility but it can't unmount


My external hard drive is a Western Digital 1.5Tb and it stoped working a few days ago.
The first symptoms were randomly ejecting, giving an error like "The disk was not ejected properly. etc" and taking too much time to mount and read the files so i thought it could be from the USB cable or maybe too much stuff on it (although i still had 200GB free), got a new USB cable and a new power adapter, but the problem remained.
On the next day i thought it would be a good idea to start saving my files to another disk, for each 1GB i took about 2 hours, so with all patience in the world i started saving the the most important files. On the next day, it didn't recognize any files, couldn't access the disk and it didn't unmount.

I dont really know what to do, so i started looking for Data Recovery Software, i ran File Recovery for Mac hoping it could get my stuff but after an entire day searching on the disk nothing showed up.
So i started to think of erasing the disk and then try to recover the data with recovering software. I don't really know if this would work, but i guess it'll be my only option for now.

When i try to erase the disk with disk utility it says:
Disk Erase failed with the error:
Could not unmount disk

After a lot of research i found this post ( http://www.justanswer.com/mac-comput...macintosh.html ), and followed all the steps in it, and I get exactly the same problems this guy did, and still can't erase the disk, neither through Disk Utility nor Terminal.

Do you know how can i solve this?

I have my life in that disk...

any help will be appreciated!
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Old 11-29-2011, 01:04 PM   #2
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Join Date: Mar 2002
Location: Anchorage, AK
Posts: 762
You do have backups, don't you?
  1. What computer do you have the drive connect to, how is it connected (USB? Firewire?) and what version OS are your running on it?
  2. Do you have any software that automatically starts? (System Prefs -> Users -> Login Items. This path may differ slightly based on question 1)
  3. If you are familiar with Terminal, you might be able to find out what process is still using the drive and keeping it from unmounting. If you already ran the command from the link you mentioned, what was the result?

Most folks around here will recommend Data Rescue and I've had good luck with it, though I haven't used the latest version.

Not sure why you feel you should erase your drive before running a recovery on it... how does that make sense?
...if only you could see what I've seen with your eyes.
- Batty, Blade Runner

They all float down here...
derekhed is offline   Reply With Quote
Old 11-29-2011, 02:30 PM   #3
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Join Date: Sep 2003
Location: Old Europe
Posts: 5,146
  • Do +not+ erase the disk.
  • Don't power the disk unless you do useful things with it, such as scraping any byte you can still read off of it.
  • Using the Console Utility, have a look at the system logs. If there are any I/O errors logged, chances are, your external disk is dying.
  • Disks are cheap, your data is not. Getting a disk in working order to re-partition or format is a piece of cake, but not your problem right now.
voldenuit is offline   Reply With Quote

can't erase disk, unmounting disk

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