Mirror contents of one disk to another

Discussion in 'Mac Basics and Help' started by iMarty, Dec 18, 2014.

  1. iMarty macrumors newbie

    Joined:
    Oct 10, 2014
    #1
    Hi,

    Just bought my first Mac and looking for some advice how to handle a back up of my data drive.

    In Windows land, I had a 2TB internal HDD that was mirrored to a 2TB external HDD using the robocopy /MIR command in a batch file. After the initial sync, subsequent runs would only copy new files and make changes to existing ones if applicable. I didn't run this on an automated schedule, just manually as and when significant changes were made, generally a weekly basis.

    Is there an equivalent command that can be run in OS X to mirror contents of one volume to another? I've seen some apps that seem to do what I require, but not sure if they're any good.

    Any recommendations would be appreciated.

    Thanks

    iMarty
     
  2. Bruno09 macrumors 68020

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    #2
  3. iMarty thread starter macrumors newbie

    Joined:
    Oct 10, 2014
    #3
    Thanks for the reply Bruno.

    I had looked at Time Machine, but it doesn't seem do what I was doing with the robocopy command in Windows. I'm not wanting to keep incremental daily, weekly, monthly backups etc.

    I should clarify that both of the 2TB drives I was using are now external to my Mac. The internal 2TB is now in a caddy and I intend to keep that permanently attached to my Mac Mini. Both drives are USB 3.
     
  4. Bruno09 macrumors 68020

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  5. Alrescha, Dec 18, 2014
    Last edited: Dec 18, 2014

    Alrescha macrumors 68020

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    Jan 1, 2008
    #5
    The command you would issue in OS X would be "rsync". It has seemingly infinite switches to control its behavior, and I recommend reading the man page. That said, the following will backup your home directory (for instance) to an external drive:

    Code:
    rsync -avP /Users/youraccountshortname /Volumes/yourexternaldrivename
    
    Subsequent invocations will perform an incremental backup. Some caveats:

    1) Time Machine (as suggested) would do a better job of it. You can turn Time Machine on and do a backup and then turn it back off.
    2) You need addition switches if you want to backup things like extended attributes (file tags, comments, etc).
    3) The supplied rsync command is getting a bit dated. There are free (BackupList) and pay-for (Carbon Copy Cloner) programs which bring their own newer versions of rsync.
    4) If you want a true (bootable) mirror, then you want Carbon Copy Cloner.

    A.
     
  6. iMarty thread starter macrumors newbie

    Joined:
    Oct 10, 2014
    #6
    Thanks for the response Alrescha.

    I'll give the trial of Carbon Copy Cloner a go as you and Bruno have suggested.

    Thankfully I have some more expendable lower capacity drives that can be guinea pigs :)
     

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