I have a USB 3.0 to Sata cable of which I will plug into a 500gb SSHD. I will try to install a completely new Mac OS X on it using the Internet Recovery option. Then transfer all of my files via USB 3.0 from the internal to the SSHD.

Afterwards, I will replace my internal HDD with the SSHD. Will this work? Will it automatically boot into my SSHD seeing as it is the only drive?

2 Answers 2


Yes. OS X supports external bootable volumes fine, and doesn't differentiate in any meaningful way between an external and internal bootable volume.

I would recommend using Migration Assistant to migrate your files, however, if possible–but you'd need a second Mac for this. A relatively easy workaround is to simply "restore" the external disk using the internal disk as the source. You'll need to first boot onto an external drive of some sort or Internet Recovery (assuming your Mac is new enough) (to my knowledge, the recovery partition won't work), then use Disk Utility from there.

  1. Select the external volume in the sidebar, then select Edit > Restore.
  2. Click the Restore pop-up menu, then choose the internal volume.
  3. Click Restore, then click Done.

I recently did this for my iMac using a time machine back up.

So I went ahead and replaced the HDD with an SSD and started the computer. I had the ethernet capable plugged in and the time machine External HDD. There was a dialogue screen that asked me if I wanted to restore from Time machine and I clicked yes and selected the backup I wanted to use. it didn't take long at all.

This would take out one of your steps.

The other way to do it would be to remove your HDD and Duplicate it to the SSD and install the SSD and start the computer and you're done. With this you must insure the SSD is the same size or larger than the original HDD.

  • 1. He doesn't necessarily have any time machine backups, so let's not use that as a solution. 2. You don't need to have an SSD/SSHD that's of ≥ capacity, just ≥ amount currently used. See my answer for better info.
    – JMY1000
    Jun 3, 2016 at 7:19
  • I didn't see where there was no Time Machine or no option to create Time Machine backups. An alternative to the Time Machine would be to create a bootable flash drive. the OP is not clear on whether or not there is a backup or that one cannot be made. As for the drive sizes I was referring to the Cloning process when addressing the Drive size. All the Drive Duplicators I have come across require a drive of equal or greater size to complete the process. Not that your suggestion won't work this is just another option with less steps. Jun 3, 2016 at 7:36
  • It's not impossible, but it's more difficult if it doesn't already exist, and would require a third drive if the flash drive isn't big enough (which it probably isn't.) Regarding duplicating the drive, that's just not the case.
    – JMY1000
    Jun 3, 2016 at 7:43

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