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Most of us never give much thought to what is happening in the background when copying files from one location to another, we simply complete the task and move on. But is there an extra copy left behind that we are unaware of? With that in mind, today’s SuperUser Q&A post has the answer to a curious reader’s question.

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

Screenshot courtesy of Arik (Flickr).

The Question

SuperUser reader BattlFrog wants to know if the Windows cache retains a copy when copying files between two USB flash drives:

I plugged two USB flash drives into my Windows 7 laptop and copied a file straight from one flash drive to the other. Would my laptop’s operating system also have a copy of that file on it somewhere by chance?

Does the Windows cache retain a copy when copying files between two USB flash drives?

The Answer

SuperUser contributors EEAA and Abraxas have the answer for us. First up, EEAA:

No, it would not. Parts of the file may be cached in memory, but extracting those parts and sorting out which parts are missing would be either incredibly difficult or impossible.

Followed by the answer from Abraxas:

I think it should go without saying, but it is perhaps worth noting that even if parts of those files are in memory, they will not stay there permanently. Things like rebooting the computer or having a high utilization of memory occurring will cause those pieces to disappear relatively quickly.


Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.