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I have been doing my own backups using rsync to a remote computer. However, due to the recommendation to have a full computer backup before upgrading to OS X 10.10 Yosemite, I am trying to undertake the task of setting up Time Machine so as to back up not only my own files, but other users on the machine as well.

My concern is whether or not Time Machine will preserve hard links. I have about a couple hundred gigabytes of images that I have organized using hard links, such that every image is duplicated several times. My external drive for use with Time Machine is 1TB, and there are about 500GB of actual unique data on the drive. However, if hard links are not preserved, the figure will be more like 2TB, which I don't have. In the past (like 4 years ago), I have read that TM didn't preserve hard links. Is that still the case?

Obviously I would like to try an experiment on my machine, but it seems like it might not go well if I don't have the space.

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Time Machine still backs up hard-linked files separately. So using Time Machine for your full system backup isn't going to work.

I've used Carbon Copy Cloner in the past for a standalone archive when doing a system upgrade. According to the documentation, this does handle hard links correctly. This has the advantage that you can boot from the external hard drive if something goes wrong during the upgrade.

  • Thanks! I've been using rsync (which with the right options does hard-link preserval properly) across the network, so I'm going to move ahead with retaining that system and excluding my home directory from the Time Machine backup. – Michael Nov 6 '14 at 16:11
  • Go for it! But note that the free 30 day trial of CCC is quite enough to get through a system upgrade, so there's no need to pay for it, and in my experience having a bootable backup can be a lifesaver. – nickcrabtree Nov 7 '14 at 16:01

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