I've installed a new HDD in my iMac, so i reinstalled OS X. I used migration assistant to set back only the settings. I also wanted to set back some other folders, but since my new HDD was smaller than the original one I wanted to dive in this later on.

Now I have setup time machine for my new installation of OS X (with the same computer name). Frankly I can't access the files/folders of the old backup anymore. In time machine the dates of the backups show up, but I can't move to them. Also migration assistant only shows the new backups and not the old ones anymore. I think the old backups are still there, since the time machine backup file is around 500 GB and the backups from the new installation are around 40 GB.

Is there a way I can get to the old backups?

2 Answers 2


I've had this happen to me when I've rebuilt our iMac. Basically the Time Machine context has become separated - unfortunately it's not just tied together by name.

What I found immensely useful is this page which will step you through the process of reconnecting the existing context to your new Mac.

[EDIT] The above link is dead, but it's still available here: https://web.archive.org/web/20170704160143/http://pondini.org/TM/B6.html

  • 1
    The information on the Great Pondini's Time machine pages has come to my rescue many, many times.
    – IconDaemon
    Commented Mar 13, 2016 at 23:13
  • The man page for tmutil, which is a tool that was suggested by the Great Pondini for this situation (pink box, if I’m not mistaken), has an excellent man page. Since the site is not updated, I suggest consulting man tmutil (via Terminal’s Help menu) on your system before using tmutil. Commented Jul 30, 2018 at 0:49

Time machine can be problematic. A couple of things to try:

  • open a folders that you can't access in finder, right click > get info, and check permissions. Does your user have read & write permission?
  • make sure your new HD disk name is the same as the old one.
  • try to access through time machine or finder.
  • give it time - there are references in the apple forums of backups not being browsable right away, but eventually becoming available.
  • Frankly, none of the above seems to cure te problem. As you were mentioning the HD disk name should be te same as te old one. I've done this. But doesn't this create any conflicts within time machine? The different installation, and different hard drives, will be backed up within the same back up file.
    – Jos
    Commented Jan 2, 2016 at 22:04

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