iMac (2012) doesn't boot from USB Clone


macrumors 6502a
Original poster
Aug 17, 2010
App Q&A testing by request.
I have a 2TB Toshiba I use to clone/back up my Macs to.

It has 2 partitions , 1 I use for the iMac (A), the other for my MBP(B).

When plugged in, Startup Disk shows both A & B. Restarting with Option Key down, shows both A & B.


Ok, so I created the iMac back up by using Carbon Copy Cloner to make an initial clone, on a freshly erased partition.

I used Chronosync to update the clone to match the active iMac drive several times before taking the iMac for a few days at the Apple Store for repair of the stand hinge.

I had found (before taking it in) that the iMac would not boot from the Toshiba Drive. It would start, show the apple icon, than turn off (just go black). I ASSUMED that this had something to do with the Toshiba's power system.

HOWEVER, this (appears) to not be the case:

1) I can boot the iMac using the Macbook Partition.
2) I cloned the imac Clone from the toshiba to a third drive that had previously had a working boot image on it, and got the same results as above (the shut down during start up).

The iMac does boot from other USB sources, as said.

SO, the question is what went wrong with the clone I made? Something with the combining CCC and Chronosync?

(This is all post-mortem...I'm just doing a fresh install on the imac now, but want to know for the future).


macrumors Core
Feb 20, 2009
- Use CCC to create your backup
- Do a test boot -- does it work?

- Do whatever you're going to do with Chronosync
- Again, do a test boot. What happens?

If no boot the second time, my suggestion is to use CCC and ONLY CCC for your backups.
CCC does a great job with incremental backups...


macrumors 6502a
Apr 28, 2012
I don't really see the need for Chronosync. Why don't you just do a CCC copy and see if it boots? (As Fish said)


macrumors 601
Aug 6, 2007
Why not just boot to disk utility via any bootable drive, and clone straight from there. I have mad clones that way for years and booting them to USB on a 2012 imac is a non issue.
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