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Whaat? DVD ISO File Checksums Different Every Time


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I'm confused.


I'm using MD5 checksum to compare two files - one a copy of the other, an 8GB DVD ISO file - one on my USB hard drive attached directly to my PC and the other on my unRAID server.


The two checksums don't match.


OK - one file must be corrupt, right?


So I ran the same checksum multiple times against the file on the USB drive. It comes up different every time!  - Dodgy USB drive or lead, right?


Then I ran it multiple times against the file on the unRAID server connected over gigabit ethernet - it also comes up different every time!


What the heck is going on?


Is there something I don't know about checksum tools not being able to accurately check 8GB files?


Is there a way I can easily checksum the file directly on my unRAID server?


I also tried two different checksum tools (Microsoft FCIV and FastSum). Not one checksum is ever the same...



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Same deal. Files don't match. Running a Memtest 86 scan now and will see what it says tomorrow. It passed one complete scan so far, so it looks like I might be OK for the RAM in my PC. Who knows though - this is just bizarre.


Also running a compare with another machine shows a mismatch between practically every file on the USB drive and the unRAID server, so I guess there was some issue copying them. WTF?  I thought there was supposed to be parity checking on read, network and write operations. This has just made me lose faith in my whole setup, rightly or wrongly.


I guess DVD ISO files are designed to be resistant to corrupt or unreadable bits, so at least they will probably still play OK...

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unraid wont verify what your copying, it protects what you gave it. if you gave if goobered files.. it protects the goobered files.


It is a always a good idea to transfer large quantity of files with a program that verifies the write.

Beyond Compare or Teracopy for example..



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