Make External HD Copy

Discussion in 'Mac Basics and Help' started by jasnw, Jun 1, 2019.

  1. jasnw macrumors 6502a

    jasnw

    Joined:
    Nov 15, 2013
    Location:
    Seattle Area (NOT! Microsoft)
    #1
    I'm moving a bunch of data from a 1TB external drive to a new 2TB drive. The two fastest options appear to be using the Restore function of Disk Utility or a 3rd party utility like CCC (which I have, and use for backups). Any comments on which of these (or perhaps some other option) is best? The only big difference I can see between these two is that since Disk Utility uses block transfers (essentially a "perfect" image of the original) and CCC uses rsync (a file-transfer utility) the CCC copied disk will use the space on the new drive more efficiently. I suspect Disk Utility might be faster, but I don't know that for certain.
     
  2. phrehdd macrumors 68040

    phrehdd

    Joined:
    Oct 25, 2008
    #2
    Test out CCC - nice to pack the disk.
     
  3. Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #3
    If you have CCC, USE IT.

    There's really not much more to say.
     
  4. mikzn macrumors 65816

    mikzn

    Joined:
    Sep 2, 2013
    Location:
    Vancouver
    #4
    Yeah if you have CCC why not use it?

    You can easily create a folder (source) to Folder (destination) task and do a one time manual copy or you can update it / sync as needed later on
     
  5. jasnw thread starter macrumors 6502a

    jasnw

    Joined:
    Nov 15, 2013
    Location:
    Seattle Area (NOT! Microsoft)
    #5
    "Why not use CCC?" is pretty much what I'm asking. I'd like to get this transfer done as quickly as possible, but not at the expense of something that might be important. I expect the block-transfer capability of Disk Utility (or even the good old Unix dd command) to be fast, should be faster than a file-by-file copy (if implemented correctly, which cannot be assumed with Apple these days), but at the cost of inefficiency in disk space employment.

    Unless I get a strong vote from someone for Disk Utility I'll just go with CCC.
     
  6. mikzn macrumors 65816

    mikzn

    Joined:
    Sep 2, 2013
    Location:
    Vancouver
    #6
    I can't think of any good reason to use "disk utilities" over CCC - especially since you have purchased a copy of CCC !

    With CCC you can either copy specific folders to the new drive - or - if you want everything transferred? - "clone" the whole drive and rename the new drive after the transfer is complete to the same drive name so the files can be found by the same path name?

    Also can't imagine it would take very long? if they are both SSD's - a little longer if they are HDD's
     
  7. chown33 macrumors 604

    Joined:
    Aug 9, 2009
    Location:
    betwixt
    #7
    I would use CCC. For one thing, it's behavior in the face of errors is more informative.

    A block-copy (via Disk Utility or 'dd') will need to copy empty unused blocks, along with all the blocks in use. If the originating disk has had some significant deletions over time, there may be significant gaps (fragmentation).

    If you think it's going to be a significant difference, you could use 'dd' to run a block copy to a disk-image and see how long it takes. Use the count=n arg with say 100 input blocks, and ibs=100m. The output of dd will tell you the byte count and data rate. You could then do a similar test with CCC copying a folder of similar size.
     
  8. jasnw thread starter macrumors 6502a

    jasnw

    Joined:
    Nov 15, 2013
    Location:
    Seattle Area (NOT! Microsoft)
    #8
    And that's my primary concern with the block-copy approach. The HDs in question have been in use for several years for rotating backups (daily incremental CCC backups to day-of-the-week sparsebundles), so I suspect things are pretty patchy.
     
  9. chown33 macrumors 604

    Joined:
    Aug 9, 2009
    Location:
    betwixt
    #9
    Then to me the answer is easy: CCC.
     
  10. Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #10
    Try using CCC to do the job.
    Then come back to this thread and give us your report on the experience...
     

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9 June 1, 2019