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I'm looking to use an external drive for a new purpose and want to see which, if any, files on it are not already on my main pc.

I've seen comparison programs that can compare folders or one drive to another. (e.g. compare internal drive c to external h) But since the files on the external might be on any of the internal drives I'm wondering if anyone knows of a program or method to compare an external drive to ALL the internal drives on a PC. (e.g compare internal drives c,d,e,f,g to external drive h)

Basically I want to make sure I can safely format the external.


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up vote 0 down vote accepted

Check out this list of duplicate file detectors. Personally, I use Duplicate Cleaner Free, but read the reviews and take a pick.

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does DCF allow you to check multiple drives at the same time? – Ian Jan 6 '13 at 23:36
Yes, you can select individual folders or drives to scan, or you can select folders or drives to exclude. – ChrisN Jan 6 '13 at 23:41

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