I just migrated from a 120 GB SSD drive to a 600 GB SSD drive. As I was lazy and didn't want to reinstall Mac OS X (Lion), I chose the following migration path:

  • I created at GPT on the 600 GB target disk with exactly the same three partitions as they are present on my old disk, using gdisk. I placed the third partition (that holds the Lion Recovery System) at the end of the disk, such that there is empty space between the system partition (holding the "Macintosh HD" labeled FS) and the recovery partition. I chose this setup as I wasn't sure whether I wanted to expand my system partition later or use the new space for a separate filesystem.
  • I plugged my old 120 GB SSD into a linux box and saved three images, one for each partion, using dd
  • Then I plugged my new 600 GB SSD into the same box and wrote the three images to the three newly created partitions, again, using dd

Then I installed the 600 GB SSD back in my Macbook Pro and started up the system. Everything works fine, with the exception that it seems to take forever for the computer to decide what partition to boot from - before the early password prompt (I use full disk encryption) I now have to stare at a white screen for about 10 seconds.

Disk Utility reports that something is wrong with the partition table that might cause trouble when booting the system:

Disk Utility

Now, fortunately, up to now they only delay booting, but don't prevent it ;) Don't be confused by the screenshot, in the meantime I created another partition holding a filesystem labelled "Storage HD".

What did I miss? Is there a boot flag or something like that for a GPT partition that I didn't set? Disk Utility is unable to "repair" anything. Also, when I boot with a Lion Installation Media and use Disk Utility from there, it doesn't report any error at all.

I am aware of the recovery from TimeMachine / old disk / etc options of the Mac OS X Installer. I'm not interested in alternative ways to migrate a Mac OS X installation, but want to understand what exactly is going on here.

  • I am jealous of a 600 GB SSD! My 250GB is so full...
    – geoffc
    May 25, 2012 at 20:38
  • 1
    @geoffc unfortunately it comes at the cost of speed... Intel only has the 600 GB with a 3G controller (Intel 320) and not with a 6G controller (Intel 510)... still... 50% faster than the Toshiba crap that Apple sells ;)
    – barbaz
    May 29, 2012 at 9:26

1 Answer 1


A PRAM / NVRAM reset (⌘-⌥-P-R on startup) fixed the delay. The Disk Utility error report remains. Started again from my old drive, the error is reported there as well... probably it was there before the migration.

  • That makes sense that it would cache the boot device. Interesting taht it would not fix it in the NVRAM itself though.
    – geoffc
    May 25, 2012 at 20:38

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