I've been backing up my MacBook Pro for 5 years using Carbon Copy Cloner. The full backup is on a partition of an external hard drive and there is a folder called _CCC_Archives which I believe stores the diffs over time.

I have upgraded the OS at least once and I'm wondering what the implications of this are.

Since upgrading from something like Snow Leopard to Sierra some of my music projects fail to open, presumably due to incompatible software. Is there some way to boot my MacBook using a backup from an older OS, capture and export some files, then reboot the MacBook to the newer OS that I'm running?

Note that I have never backed up the Mac since upgrading the OS because I did not want to corrupt my backup if it would in fact be irreversibly corrupted by this change. So the backup drive only includes backups using Snow Leopard.

The setting I use for backups in CCC is called: "Maintain a backup (Archive modified and deleted files)"

And below this I see:

• Files and folders on "My Passport" that are not present on "Macintosh HD" will be archived.

• Previously backed up files on "My Passport" will be updated only if the size or modification date differs.

• Older versions of updated files will be archived.

• CCC will not prune archive content.

  • first question : what did you tell ccc to do ? a full backup or incremental ? Then, when you did previous system upgrades was the next backup full or not? This will affect how you can go backwards. You could consider installing previous systems on an external drive, booting from there then rescuing those files...
    – Solar Mike
    Commented Jun 30, 2017 at 22:16
  • I have never backed up since upgrading my OS. I updated my question with the settings I use. I think these were "customized" settings.
    – JacobIRR
    Commented Jun 30, 2017 at 22:20

1 Answer 1


Based on the info in your question you should be able to restore an appropriate backup image to another external drive.

Once you've done this, boot your Mac into the Startup Disk Manager (i.e. press and hold the option key as you boot up) until you see the drive options appear. Select the disk you've just restored the Snow Leopard backup to and press enter to see if you can boot from it.

If it boots okay, then you can try to convert the files you want to use in macOS Sierra.


1 If your drive doesn't appear in the Startup Disk Manager, there are a number of possible reasons for this. If this happens to you, then while you're in the Startup Disk Manager you can try pressing the option+shift+command+. keys to see if your external drive has optional ROM firmware available.

2 If you can't boot up from the drive, refer to the Help! My clone won't boot! page for a detailed list of possible causes/solutions.

  • hmm ok. I'm getting a large drive that will be able to hold many separate backups. Must this drive be partitioned for each OS and is "bootability" a requirement for restoring a machine to a given backup state? or is it possible to just boot a given machine and then dump files onto it from a drive and have those files become the new system?
    – JacobIRR
    Commented Jul 1, 2017 at 3:12
  • I'm not sure I understand your question, so maybe I'll try and clarify what I'm saying and we can go from there. You just need to restore one of the backups (i.e. one you know that has Snow Leopard or whichever OS it was) onto another external drive. Now, if that backup also has the files you need to access to try and convert, that's all the better. But that isn't necessary because you can still copy/access the relevant files from another drive if necessary. The key thing for you is that you need to boot into an OS that runs the software you need to access/convert your music projects.
    – Monomeeth
    Commented Jul 1, 2017 at 3:28
  • In terms of the new external drive, you will need to ensure it is formatted correctly for use with macOS. If unsure, refer to Preparing your backup disk. Since you're getting a new drive, you may also want to refer to Choosing a backup drive.
    – Monomeeth
    Commented Jul 1, 2017 at 3:28
  • Ok that makes sense. So I am going to 1) get my new drive and back up my mac to it. 2) Try booting my mac from the older backup drive using the most recent Snow Leopard backup, troubleshooting as necessary. 3) I can modify/export files as needed in this temporary state. 4) Then I either need to restore to the Sierra backup, or this will happen automatically. Then I can safely backup my mac using the current Sierra state since my files have been either modified/exported. Is this what you're proposing? (I'm going to make a separate question about the partitioning issue I mentioned)
    – JacobIRR
    Commented Jul 2, 2017 at 0:08
  • That is one way to go, but what I was suggesting is: (1) get new HD, (2) restore from one of your backups to the new HD, (3) boot up your Mac while holding the option key down until you see the SDM, (4) select the new HD you've just restored to and press enter, (5) wait for your Mac to boot into Snow Leopard, (6) modify/export your files as needed in this temporary state, (7) reboot your Mac as normal from the internal drive. NOTES: This way you're not touching the current macOS installation and not risking booting up directly from your current backup (both are basically left alone).
    – Monomeeth
    Commented Jul 2, 2017 at 3:00

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