Disk Util cannot unmount ext HD to format or partition

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Disk Util cannot unmount ext HD to format or partition

Computer: MacBook Pro Retina 13" latest model. All updates have been applied.

I have a 1TB WD external harddrive. It has 2 partitions (1 FAT32, 1 Mac OS Extended). This drive was working properly until one day it stopped mounting.

Problem:

- Mac OS Extended partition: Will not mount. I can see it greyed out in Disk Utility. The entire drive will not unmount.

- FAT32: Mounts in OSX but will not unmount. I can access FAT32 partition via Parallels (Win7).

Bigger Problem: I'm cannot re-format or re-partition the drive. Disk Utility provides an error that the drive cannot unmount.

Any help is greatly appreciated.

MacBook Pro with Retina display, OS X Mavericks (10.9.1)

Posted on Feb 23, 2014 6:11 PM

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Answer 1

RBSL Author

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Feb 23, 2014 6:58 PM in response to RBSL

I made a mistake in the original post. I CANNOT access the FAT32 via Parallels because it will not unmount from OSX.

This is how I fixed it....

Booted up my Windows laptop and used Computer Management to delete both volumes (partitions).
Re-partitioned as 1 partition (ex-fat) and formatted.
Booted up MacBook and used Disk Utility to re-format as Mac OS Extended.

This appears to work fine, and I am able to use it for Time Machine now.

My question now is: How could I have accomplished this in OSX? I know some people will say maybe the drive is going bad. For this question, let's assume it's ok.

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