Cloning data drive, speed question

Discussion in 'macOS' started by kirkbross, Nov 30, 2014.

  1. kirkbross macrumors 6502a


    Mar 6, 2007
    Los Angeles
    I just bought a 3TB drive to replace a 1TB drive that's getting close to capacity. Both are internal sled drives and I so I formatted the new disc and just selected all the folders in the old drive and dragged them to the new drive. It says "about 3 hours" left.

    I'm wondering if that time estimate is a matter of the sheer volume being copied or if it's faster to use a cloning app like CCC or File Synchronization... i.e. if 3rd party applications copy in a different, smarter, faster way?
  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Some of the file copy/clone apps have error checking and such to make sure all the files got there in one piece, but I don't think they would really be faster than what you did. It just takes time to move all that data across two drives.
  3. chown33 macrumors 604

    Aug 9, 2009
    Sailing beyond the sunset
    Rough data-rate calculation:
    Divide the total data to copy (1TB) by the estimated time (3 hours) to get result in MB/sec.

    3 hours = 3 * 3600 (secs/hour), or about 10,000 secs (1E4)

    1TB is about 1E6 MB (megabytes) of data.

    So the data rate is roughly 1E6 / 1E4 = 100MB/sec. ​
    100MB/sec seems fairly reasonable to me, given the roughness of the approximations.

    In any case, the best rate obtainable will be no faster than the slowest performing element (source disk, its interface, memory, target disk, its interface).

    Or you could launch Activity (in /Applications/Utilities), choose the "Disk Traffic" sub-pane, and see what the actual data-rates are.

    Or maybe not, since original post was about 3 hours ago and it's probably finished by now.

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