Upgrade iMac to Fusion SSD for Speed

TechDC iMac 27” 2017  HDD to SSD (should work if there’s no fusion too)

I recently upgraded a 2017 iMac with a Fusion drive (SSD plus hard drive) to an SSD only Fusion drive by replacing the hard drive (HDD) with an SSD. While the idea of a fusion SSD may sound weird, it works great. The SSD in iMacs (especially 2017 and beyond) are much faster than a standard SSD, so you still get the fusion benefit of combining a faster and slower drive. And replacing a HDD with SSD is a huge speed improvement that can make a computer feel much more responsive.

Parts List

Crucial 2TB SSD ($207) – this is a hair faster than the Samsung.  

Or

Samsung 4TB SSD ($400) – not a lot of 4TB options on amazon

iMac adhesive strips + opening wheel

Generic phone and iMac work kit (has the necessary plastic cards and scraping tools and many other parts not used)

3M pads to adhere SSD inside iMac

Preparation Steps (note that a colon on a step means its a terminal command)

Step – Backup via Time Machine (to be restored later)

Step – Create a macOS (Mojave) boot usb drive (9to5Mac Article)

Step – Boot off usb drive (hold option key) and secure erase the HDD.  Since the HDD will be left inside the iMac, best to be safe and securely erase it.

Step – Launch Terminal from top menu Utilities 

Step -: diskutil list (to determine the name of the synthesized fusion disk drive such as /dev/disk2)

Step -: diskutil secureErase 0 /dev/diskX (where diskX is the name of the disk to HDD) (This can take hours depending on your drive size) (this does a single pass of zeros written for security, there are options to do more)

Installing SSD Steps 

Based on https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+Hard+Drive+Replacement/30522

& https://www.ifixit.com/Guide/How+to+Add+An+SSD+To+The+27-Inch+iMac+(Late+2015)/67309

Step 1 – Lay iMac on its back 

Step 2 – use roller tool to cut thru glue

Step 3 – use plastic cards to separate remaining glue (takes time and work)

Plastic Cards

Step 4 – lift up screen ad prop up with boxes

Step 5 – unplug old HDD

Step 6 – plug in new SSD

Step 7 – attach adhesive strips to SSD and stick to iMac wall, as near HDD as possible.  Slight angle is needed for opposite corners of SSD to touch curved wall.  I only put adhesive strips on opposite corners of the SSD.

Step 8 – move prop up boxes to inside the iMac so you can do the next step

Step 9 – remove all adhesive that held screen in place (takes the most time)

Step 10 – use alcohol wipes to clean up where the strips go

Step 11 – apply new strips

Step 12 – lower screen back down to adhere to new adhesive strips

Step 13 – Boot up iMac and begin post install steps

Post Install Setup Steps (colons refer to terminal commands)

Step 14 – Boot off macOS usb drive by holding down Option

Step 15 – Launch Terminal from top menus

Step 16 -: diskutil list (to determine the names of the old internal SSD and new added SSD)

Step 17 -: diskutil coreStorage create fusion /dev/disk1s1 /dev/disk0s1 (where disk1s is the faster internal SSD and disk0s1 is the new SSD

Step 18 – a unique UUID will be displayed identifying the new volume group.  Copy this to clipboard.

Step 19 -: disktuil coreStorage createVolume UUID-FROM-PREV-STEP jhfs+ “Macintosh HD” 100% (This note is likely changing those quotes to evil quotes, you’ll want to type this up with non-evil quotes so a reader can copy them)

Step 20 – open disk utility

Step 21 – Erase the new Macintosh HD with the APFS option

Step 22 – Restore from Time Machine

Step 23 – Open Photos (does restoration for a long time)

Step 24 – Open Mail (does some migration)

About: Rick