Using Disc Utility for Backup Clone

Discussion in 'macOS' started by Zen5656, Mar 16, 2017.

  1. Zen5656 macrumors member

    Oct 23, 2010
    I just upgraded my MacBook Pro Retina SSD and found out that you can copy/clone a drive including recovery partition by the option Restore in Disc Utility. So you can basically restore your OS X partition to a previously formated external drive of same size or bigger...

    Is there any disadvantage using this as a backup method? Why the hell did I buy CCC?

  2. chown33 macrumors 604

    Aug 9, 2009
    Restore makes a complete copy of everything, every time (no deltas). CCC only copies things that changed.

    I don't think Restore will restore to a partition of a different size. It must be exactly the same. CCC will happily copy to larger or smaller partitions, as long as the overall space allows it.

    Restore is all or nothing. CCC will let you choose what to restore, e.g. you can omit printer drivers or huge sound libraries.

    The utility that underlies CCC is called 'rsync'. I forget what underlies DU's Restore, but it might be 'dd'. You can read their man pages to see other differences.
  3. Zen5656 thread starter macrumors member

    Oct 23, 2010
    Yeah but since my backup is always 1:1 and I format the drive before it should work the same. The problem I had during upgrade is that my "added to" timestamps where always lost using ccc as it copies the files again. So my big Download folder, sorted by "added to", became unstructured. Then I used Disc Utitlity Restore and it worked as the complete partition blocks are copied.

    Restore copied to a partition of bigger size (256 to 512 gb SSD) for me so it works.

    I will get into that rsync and dd topic
  4. chown33 macrumors 604

    Aug 9, 2009
    I may have misremembered that constraint. It was at least a few years ago that I evaluated Restore for doing backups, so I can't recall exactly why I decided against it.

    Double-check that the restored partition actually remains at the original size (reboot after Restore). I know 'dd' is able to write a smaller source to a larger target, but the resulting file-system (when the source is a file-system) may not cover the larger size. Or maybe Restore used to have a restriction that's since been lifted.
    --- Post Merged, Mar 16, 2017 ---
    Forgot to address this.

    I think "added to" is in the metadata store, i.e. the Spotlight metadata. So if that's not being preserved by CCC, then it can't be restored. There may be a CCC option to preserve it, I don't recall.
  5. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    I believe the issue is if the source partition is larger than the destination partition, DU restore will not work, even if the data would fit. So a 500GB partition with 100GB of data will not DU restore to a 256GB partition. But if the destination partition is larger it will work fine.
  6. chown33 macrumors 604

    Aug 9, 2009
    I knew and was confident of the "source is larger" constraint. It's the "source is smaller" one I was unsure of. As I said, it's been a while since I evaluated this, and I'm uncertain whether it was a real constraint at the time, or whether I've misremembered it. It was probably in the days of 10.2 Jaguar that I did that evaluation.

    I also realized that the partition's size is the deciding factor, not the amount of space in use. I didn't point that out, and now you have, so thanks for clarifying that point.

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