I am planning to follow the instruction from MacSale to add an additional SSD to a mid-2011 27" iMac (https://youtu.be/eFHvIrdm9So)

It will be placed under the optical drive.

enter image description here

I want to make this drive the boot disk and do a fresh install of macOS to this drive. However the video did not touch on this area.

Based on what I know, I think I can

1) Start up the system after the installation is complete.

2) After chime, I will use Command (⌘) – Option (⌥) – R combination to boot into internet recovery

3) install macOS to the new drive

However I am not sure how to permanently boot from the SSD drive.

In summary, my questions:

a) Is my plan of 'internet recovery ' going to work?

b) how to permanently boot from the SSD drive?

2 Answers 2


In system preferences, there is a selection for startup disk. You should be able to select your new drive.

  • Also, if they for some reason end up with two drives that are bootable, they can choose which to boot to by holding the option key while the system starts.
    – jbwar22
    Nov 25, 2017 at 15:17

Actually, High Sierra was built for what you want to do. This version of macOS introduces Apple File System (APFS) partitions. What you want is a single EFI and and APFS partition on each internal drive. You then construct a container which encompasses both drives. This container will know which of the two drives is the faster SSD. You then install macOS into this container. The installation process will also include the recovery volume in this container. The advantage to this approach is the software used most often will automatically be stored on the faster SSD.

You will probably want to first create a USB flash drive High Sierra installer. The instructions are given at How to create a bootable installer for macOS.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .