Copying 10,000 files? Any chance of losing some of them?

Discussion in 'Mac Basics and Help' started by 98707, Mar 13, 2008.

  1. 98707 macrumors regular

    Joined:
    Feb 15, 2007
    #1
    If I was to copy large amounts of files for backups is there any chance that the computer would accidently miss certain files or does this just not happen?
     
  2. GimmeSlack12 macrumors 603

    GimmeSlack12

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    Apr 29, 2005
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    San Francisco
    #2
    I won't say it's impossible that a file or two won't get corrupted, but I have confidence that nearly (99%) every file would get backed up with no problems. If anything move the files in batches (i.e. 2,000 at a time).
     
  3. motulist macrumors 68040

    motulist

    Joined:
    Dec 2, 2003
    #3
    Just do a 'compare folders' process after the copy. That'll confirm if the folders are bit for bit copies, or if anything is different. Toast has a compare function, other software probably does too.
     
  4. mason.kramer macrumors 6502

    mason.kramer

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    Apr 16, 2007
    Location:
    Watertown, MA
    #4
    99% is a _horribly_ low success rate for something as important as file copying.

    Fortunately, GimmeSlack12, the success rate is much higher. Rest at ease: if you attempt to copy files using Finder, and Finder does not report any failure messages, it means that none of your files were overlooked. You can feel secure in the knowledge that your files were safely copied without looking through them all.

    Edit: If you want, you could Get Info on each folder and check that they are the same size by way of confirmation. But don't worry, they will be.

    I should say that, though the copy operation is not a significant point of failure, physical disks are a significant point of failure, so watch out for old / crappy harddrives. The safest place is actually optical media like a DVD.
     
  5. GimmeSlack12 macrumors 603

    GimmeSlack12

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    #5
    You know the forums are just impossible to anticipate. If I say 100% Go For it No Problem! I'd get crap from someone saying this or that could go wrong and that I'm full of it.

    Yet when I'm realistic about a 99% success rate I get "horribly low success rate". Jeez, I guess 99.9999999%. Happy? Talk about splitting hairs.
     
  6. orpheus1120 macrumors 65816

    orpheus1120

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    Jan 23, 2008
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    Malaysia
    #6
    lol. Yes I agree. :)

    Such is human nature.
     
  7. mason.kramer macrumors 6502

    mason.kramer

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    Watertown, MA
    #7
    99% and 99.9999999% are extremely different numbers.

    If there were only a 99% success rate, a 10,000 file copy missed 100 files! Can you imagine? No installation would ever be successful!
     
  8. GimmeSlack12 macrumors 603

    GimmeSlack12

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    Apr 29, 2005
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    San Francisco
    #8
    But we aren't talking about the installation of anything. So your post is irrelevant.
    (See what I did there?)
     
  9. gnasher729 macrumors P6

    gnasher729

    Joined:
    Nov 25, 2005
    #9
    As a rule for "good enough": The copy can go wrong for reasons that have nothing to do with the OS. Like a meteorite coming down through the roof and destroying your Mac. So what is your expectancy of success if you take that into account?

    Just checked: Hard drives have an MTBF (mean time between failures) of about 500,000 hours. If you copy 10,000 files in one minute, chances that your hard drive fails fatally during the copy is one in 30 million. Probability of success is therefore at most 99.999997 percent.
     
  10. GimmeSlack12 macrumors 603

    GimmeSlack12

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    #10
    Swarm of bees is actually what I had factored in.
    EDIT: I like the way you think Gnasher.
     
  11. idonotliketostu macrumors 6502

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    Feb 28, 2008
    #11
    I hate copying things to optical disc. they damage so easily
     
  12. runplaysleeprun macrumors 6502a

    runplaysleeprun

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    Jul 27, 2004
    Location:
    Chicago, IL
    #12
    files are copied in an installation... for all we know he could have been talking about an installation that involved copying 10,000 files. A 99% success rate in copying files is really, really low. But, its not 100%. But of those times that it fails, it will probably tell you something f'ed up, (or you will see the meteorite crater where your computer used to be, as mentioned above) better improving your odds for a successful transfer by allowing you to do it again.

    Bottom line: you're fine unless it tells you there was a problem.
     
  13. GimmeSlack12 macrumors 603

    GimmeSlack12

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    Apr 29, 2005
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    #13
    Pretty sure he wasn't talking about an installation. But that wasn't really my point anyway for that post, I was just splitting some more hairs ;)
     
  14. Makosuke macrumors 603

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    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #14
    Semantics on percentile chances aside, if the original poster is just talking about copying files to another drive, then the chances of problems are functionally nil past what you usually have when working on a computer (lighting strike, massive spontaneous hardware failure, etc); it just doesn't happen. I routinely move hundreds of thousands of files around between drives (both locally and over a network) for institutional server backups without any issue.

    If something DID go wrong, the OS should tell you, though the issue is always some sort of permission issue, not hardware problems. To be extra paranoid, any number of backup or synchronization programs will double-check the files after copy to make sure there were no problems; I use Sync personally (also because it can be set to only copy changed files, which with a volume containing 200,000 files is nice).

    If we're talking about optical disc, the answer is "if there's an error burning the disc, the Finder or Disk Utility will tell you when it verifies it". The verification process reads back the entire burned disc and compares it to the original files to make sure there aren't any problems.

    Optical discs can, of course, go bad later, either due to scratching or (if you wait long enough) media degradation due to sunlight, manufacturing error, whatever, but that is unavoidable with any media format (eventually SOMETHING is going to go bad--even paper rots). Generally if you have a good burn, and decent media, and you store it carefully, it'll be good for quite some time.

    When I'm being extra-paranoid, I burn the same archival copy onto two different brands of media, and every once in a while (maybe annually) check an individual disc from each of the spindles I bought, figuring that if one goes, they're probably all going, so I'll notice it, and that two brands from two different spindles aren't likely to both spontaneously "rot" at the same time.
     

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