Susceptibility to Corruption of Aperture Library Copy

Discussion in 'macOS' started by gwelmarten, Jan 26, 2013.

  1. gwelmarten macrumors 6502

    Joined:
    Jan 17, 2011
    Location:
    England!
    #1
    Hi There

    I am heading back and forth to University. Every year, I come home for 4 months. When I leave home, I copy my aperture library file onto an external HDD and take that with me. This becomes my active aperture library file. When I get home again, I replace the version on my home iMac with the version on the external HDD.

    What is the probability that in moving a 200gb library, something will corrupt or some pictures will become unusable, or be missing from the library database file, with every copy? Is it like 99% of the time everything will be ok?

    I know for the future I can use a checksum, but haven't done so in the past. I just want to think about my current reliability compared to previous versions so I feel safe removing old versions.

    Sam
     
  2. switon macrumors 6502a

    Joined:
    Sep 10, 2012
    #2
    RE: rsync and Finder...

    Hi gwelmarten,

    I assume that when you say you copy your Aperture library you mean that you use the Finder to perform this copy. I don't know exactly how much checking the Finder is doing during its copying, but I believe it is doing a fair amount since it seldom makes copy errors.

    On the other hand, if you want to be absolutely certain of an exact copy, and in a relatively automatic way, across a network or locally, then you might consider the built-in "rsync" utility. It performs a copy of just those modified files and does so in "archive" mode, meaning that all ownership, group, permissions, links, and modes are preserved during the copy. In addition, you can force rsync to do checksums so that it will checksum the copy and compare it to the original to make certain that the copy was exact. It will also do its communications in compressed form, minimizing the amount of data transferred. And rsync will do all this differentially, so that only the changes to a directory structure will be copied. In addition, since rsync can occur over an encrypted channel, you can rsync your files over the Internet without worries about security.

    ...just another thought on how to perform your copy, especially if you are worried about corruption during the copy...

    Regards,
    Switon
     
  3. gwelmarten thread starter macrumors 6502

    Joined:
    Jan 17, 2011
    Location:
    England!
    #3
    Hi Switon

    Thanks for the tip - I do use rSync already with some local files, but I'm hesitant about doing with it with something as complex as an aperture library.

    Does anybody have any idea just what the general chance of corruption of data is whilst copying it in Finder? And back off of a HDD?

    Sam
     
  4. switon macrumors 6502a

    Joined:
    Sep 10, 2012
    #4
    RE: rsync vs. Finder...

    Hi Sam,

    I'm sure you already know, but a lot of very large and complex software projects use rsync, for instance the MacPorts project uses rsync, and I believe that the Tex Live Utility uses rsync for its updates, and for that matter the Carbon Copy Cloner backup program uses rsync to produce its differential clones. I think you would find less risk of file corruption using rsync (especially with checksumming -- guaranteeing an exact copy) than perhaps with the Finder.

    In other words, rsync is already a standard protocol used for syncing systems that are considerably larger and more complex than an Aperture library. Personally, I would not worry about rsync. Just my opinion, of course.

    Regards,
    Switon
     

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