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Disk utility error : disk could not unmount

Bennieboy©

macrumors 65816
Original poster
Jan 15, 2009
1,276
1
england
Hey guys, i'm trying to format a spare external, it's currently formatted to ms-dos for back up dutys on my PS3 but i want to change it to mac os extended

i've just plugged the drive in ( USB ), nothings running on it, or open on the computer from the drive, but disk utility wont erase it, i've checked permission and everythings fine but it just keeps giving me this error

google and apple fail, only thing i can find linked to it refers to operating systems running on the drive,
 

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BlueRevolution

macrumors 603
Jul 26, 2004
6,054
2
Montreal, QC
Usually this error means that some file on the partition is in use. Try relaunching Finder by control+option+clicking on the Finder icon in your Dock and selecting Relaunch. You can also try unmounting the partition manually by selecting it in Disk Utility and clicking Unmount in the toolbar.
 
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tigerfan34

macrumors newbie
Oct 20, 2009
5
0
Usually this error means that some file on the partition is in use. Try relaunching Finder by control+option+clicking on the Finder icon in your Dock and selecting Relaunch. You can also try unmounting the partition manually by selecting it in Disk Utility and clicking Unmount in the toolbar.

I'm having the same issue. I tried what you suggested and it didn't work. I'm trying to reformat a thumb drive (4gb). The drive won't allow me to delete anything off of it. I get the can't unmount message when I try to reformat. Any help would be great. Thanks.
 
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Zwhaler

macrumors 604
Jun 10, 2006
6,905
1,255
I'm having the same issue and relauching the Finder does not help. I can't find a whole lot of other resources on the web instructing me how to format this drive with this error message.
 
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