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Re: Not constant sha1sum

Subject: Re: Not constant sha1sum
Date: 10 Sep 2007 17:29:08 -0000
If I'm reading your post correctly, you have an entirely Linux system (NOT 
mounting a remote SMB filesystem) that when you perform a SHA1Sum on a file 
you're getting different hashes? There are only a few things I can think of 
that would cause this:

1.) The file is changing but it's unlikely given your second hash matches a 
previously generated hash (I'm assuming from your comment).

2.) The SHA1Sum app isn't reading data in a consistent manner. This can be 
caused by a number of systems-level issues related to reading data:

 *) The Adaptec RAID driver,
 *) a bad implementation of the "read" call in the SHA1Sum app,
 *) failing disk cache,
 *) pick your random SysAdmin issue...

Linux doesn't complain as loudly as Windows does  with these kinds of issues. 
I'd recommend copying the image off to another storage volume and trying to run 
the hash again. That would at least tell you if it's storage subsystem related. 
As a note, I'd recommend using dcfldd to copy it...

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