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Accidentally formatted an important external 500GB hdd yesterday. Not an SDD, 2.5".

(Quick) formatting occured while installing windows xp on it. I had the wrong usb drive plugged in. ~600MB are overwritten now of a once nearly full 0.5TB data disk. I need to get the data back.

My first reaction was to make a dd copy onto a blank, windows explorer readable different 500GB SATA hdd which I plugged into my usb jack by an usb2.0 - to - ide/sata adapter.

After a night's copying, finishing successfully now, the drive is not readable, at least not with windows explorer.

The original, accidentally formatted and windows installed usb external drive is readable. It is 500.105.736.192 Bytes of capacity.

The blank rescue drive plugged by the adapter was ntfs formatted and blank and readable in the explorer. Now it is not readable. It is 500.104.687.616 Bytes of capacity. Thus, my rescue disk was slightly too small:

C:\Downloads\dd-0.5>dd if=\\.\e: of=\\.\d: bs=500M --progress
rawwrite dd for windows version 0.5.
Written by John Newbigin <>
This program is covered by the GPL.  See copying.txt for details
953+1 records in
953+2 records out

From a layman's point of view though, if at the end there is 1MB missing, is that being a problem?

Why can't it be read?

Is it a good idea to change the rescue drive into a rescue file? Like in

C:\Downloads\dd-0.5>dd if=\\.\e: of=\\.\d:\rescuefile.img bs=500M --progress

Will the rescue file fit on the (slightly too small) SATA hdd?

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use recovery data tools – matzone May 14 '13 at 10:26
@matzone That is to dangerous an advice because it is vague. Panny should treat the drive 'with silk gloves on', i.e. try things that he controls and maybe even can revert, not use some brute force recovery tool that may make matters worse. – Jan Doggen May 14 '13 at 10:29
@JanDoggen : Panny said I need to get the data back. .. that's why – matzone May 14 '13 at 10:32
Never used windows version of dd but quite a bit in OSX: you set the block size to 500M, that is odd, normally bs=512 for 512byte. You needed to check it with chkdsk in windows os first, it would tell you (in OSX: diskutil info /Volumes/your_volume). BTW it wont fit just because it is bigger. Normally yuo want bigger HDD for rescue image. Then you have o just mount it. – Boris G Dec 17 '15 at 4:23

WinHex is very good at this. However it really depends on whether/what kind of harm was done to the partition map and the file system meta data records.

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