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.
Crucial 2TB SSD ($207) – this is a hair faster than the Samsung.
Samsung 4TB SSD ($400) – not a lot of 4TB options on amazon
Generic phone and iMac work kit (has the necessary plastic cards and scraping tools and many other parts not used)
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
Step 2 – use roller tool to cut thru glue
Step 3 – use plastic cards to separate remaining glue (takes time and work)
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)