I have a Mid 2014 Retina Macbook Pro (MacbookPro11,1), running latest Big Sur. I want to upgrade to a 1TB SSD. I bought a compatible SSD from OWC, so my question is what's the best way to get all my stuff over onto it? Seems like there are three possibilities:

  1. Clone existing SSD to new one, enlarge partitions, then boot to it. I don't think I can do this, because I don't have the special proprietary SSD enclosure to mount it (and they're like $60 for something I'll use once). Also I'm not sure this will work due to Big Sur's system partition signing.
  2. Back up existing SSD to a HFS-formatted external drive (I have a 2TB rotating drive in a USB 2 enclosure I can use for this), swap in new SSD, install MacOS fresh (from a recovery drive?), then restore apps & data from backup.
  3. Back up existing SSD to external drive with CCC, swap out SSD, boot to backup drive, then restore to new SSD using CCC. This seems unlikely to work due to Big Sur's system partition signing.

If I use option 2, is it best to use Time Machine & restore from that? Or use Carbon Copy Cloner and then Data Migration? And also how do I install MacOS on the new SSD? I'm guessing I create a bootable USB recovery drive and use that.

1 Answer 1


There is a way, without any external software via the asr command. If you have an external drive with a GUID partition scheme this is fine. You have to create an APFS container on the external disk (I suppose you can do it) then run the clone command on this disk :

The terminal command :

diskutil list

will help you for the rest

It's necessary to give in source the volume which is entitled:

Snapshot com.apple.os.update.......

and in destination (target) the APFS container created on the external disk

sudo asr --source /dev/diskxsys1 --target /dev/diskz --erase

The cloning will be done and then you have to test that you manage to start on this external drive. If so, it will suffice to mount the new SSD, format it in APFS and do the opposite.

  • Thanks for this. I ended up using a trial of Carbon Copy Cloner, in ASR backup mode (they call it "legacy" and it's deprecated but it works). It essentially does your asr command above, but it figures out the proper snapshot ID and uses some other options. It worked great; I was able to boot from the backup clone, and restore to the new larger SSD, then boot from that. Didn't even have to enlarge any partitions or anything.
    – GaryO
    Commented Oct 6, 2021 at 17:01
  • 1
    Great. Happy for you. CCC is the best application for cloning. But the asr command I give you do also the job. ;-}
    – user415185
    Commented Oct 6, 2021 at 17:33

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