About 20GB difference between internal and backup HDD

Discussion in 'OS X Mavericks (10.9)' started by bigpoppamac31, Nov 7, 2014.

  1. bigpoppamac31 macrumors 68000

    Joined:
    Aug 16, 2007
    Location:
    Canada
    #1
    So both my hard drives are 500GB in size yet my backup drive has 20GB more space available than my internal drive. The internal is an SSD whereas the external in an HDD but I doubt that makes a difference. I use CCC to clone my drive and if I'm doing it right (which I believe I am) than both drives should have the same space available right?? Anyone know why I'd have that much difference in space?
     
  2. old-wiz macrumors G3

    Joined:
    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #2
    The drive clone programs such as CCC or SuperDuper do not copy cache files and some other files - they have an internal list of files that do not need to be copied. I use SuperDuper and have done a clone then booted from the clone and all is well.
     
  3. m4v3r1ck macrumors 68020

    m4v3r1ck

    Joined:
    Nov 2, 2011
    Location:
    The Netherlands
    #3
    Yes, always test your clone! Better safe in between than sorry when depending on your backup!
     
  4. Bruno09 macrumors 68020

    Joined:
    Aug 24, 2013
    Location:
    Far from here
    #4
    You internal Mac OS X partition has a sleep image file which is the same size as your RAM, i.e if you have 16 GB of RAM, the sleep image file takes ~16GB of space.

    CCC and other backup softwares do NOT copy this (empty) file (+ some cache files), therefore the backup drive has always more free space than your internal drive.

    As said above, it is important to check that your clone is bootable and fully functional.

    (the sleep image is used to copy the RAM content when the computer goes to hibernation mode)
     
  5. sharon22 macrumors regular

    Joined:
    Oct 19, 2014
    #5
    @Bruno, I didn't know that!
    I learn something new from this forum just about every day. Lots of it from stuff you said!
    Thank you!!
     
  6. old-wiz macrumors G3

    Joined:
    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #6
    Better yet make multiple clones! I have 4 per machine which I rotate, so I always have a backup point. 1 clone I store in a fireproof box... It also helps if you do a software update or add a new program and things get really messed up.
     

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