File comparison fundamentals?

Discussion in 'Mac Apps and Mac App Store' started by toke lahti, Mar 26, 2016.

  1. toke lahti macrumors 68000

    Joined:
    Apr 23, 2007
    Location:
    Helsinki, Finland
    #1
    I'm moving terabytes of my archives to new disks and noticed that kdiff3, which I have been using to verify copied folders, is choking when giving multigigabyte 7z'ed files to verify. Biggest memory used by kdiff3 in Activity Monitor was 49GB...

    So, I looked other choises and found old "File Compare 1.1" by Softhing.
    Would be nice to be able to choose 3 files to compare (since I'm always making 2 backups), but I'm thinking about how reliable this app is?
    It calculates md5 of a multigigabyte file, which is in a NAS with 1Gb connection, in a few seconds!
    Are these md5's precalculated in filesystem?
    Would it be more sure to re-calculate?
     
  2. toke lahti thread starter macrumors 68000

    Joined:
    Apr 23, 2007
    Location:
    Helsinki, Finland
    #2
    Or is it that checksum calculation is done by filesystem itself anf therefore the content of NAS doesn't have to be read or copied to computer where I use File Compare?

    Should I move this question to some other area?
     

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