I am planning on formatting the new 2 TB SSD in AFPS format before I install it. So for a late 2014 27' iMac with a 1 TB HDD and 128 GB blade (currently running Mojave), I DO NOT NEED TO SPLIT the fusion drive before I replace the HDD with an SSD? (Per Max’s NOV 2019 updated comment regarding not having to split the drives before replacing the HDD - posted in Answers so my post was more visible): I then store User home folder on the larger SSD, and macOS and other apps run off the faster PCI-based SSD. Installed Mojave onto the 128GB PCI “Blade” Flash and formatted the other SSD.

Replaced that with a 500GB SSD which is SATA3. I recently did this prior to replacing the slow spinning disk that comprised the 1TB of my Fusion Drive. This command will split your fusion drive, and leave you with two new drives to format via Disk Utility (which you can run in the same USB Booted environment you’re already in).įormat them (the SSD and the other drive) as whatever you want. Let’s say that virtual container disk is identified as “disk0” You can see how the text output of the drive structure is hierarchical. This is made up the PCI Flash and the other spinning drive. Then make note of the “virtual disk” that is the “Fusion Drive”.