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Can a fusion drive be converted to APFS?
Now that I upgraded my system to Catalina, I wanted to format this fusion drive volume in APFS (currently running Catalina from external hard disk drive, not this fusion drive). But the conversion always fails with either of these 2 error messages:
Can a SSD be converted from HFS to APFS?
Many web pages claim that when you install 10.13 on an SSD, you have an option to convert to APFS. Many others claim that when you install 10.13 on an SSD, you will be converted to APFS whether you want it or not. Neither was the case for me.
How to convert Mojave from USB to APFS?
Afterwards, installation of Mojave from the USB suceeded too. To convert to apfs: diskutil apfs convert . The correct disk seems to be – in my case – /dev/disk2 according to the Details of the DiskUtility.
Can a fusion drive be converted to a SSD?
However, I upgraded the HDD to a Samsung SSD and combined it with the original SSD to create one large CoreStorage logical volume (can’t call it “Fusion” anymore.”) While trying to convert this logical volume, I ran into all of the same issues you did, so I was able to replicate the problem.
When you now upgrade a Mac with a startup Fusion Drive to Mojave, that drive will be converted to APFS; you don’t have an option. Before explaining how Mojave’s version 3 APFS handles Fusion Drives, let me remind you how they work in good old HFS+.
How many volumes does a fusion drive have?
The hard disk in the Fusion Drive has one declared volume: disk0s2, an APFS secondary physical store, which is designated for auxiliary use. The SSD also has a single declared volume: disk1s2, the APFS main physical store. The APFS container for the Fusion Drive as a whole has four volumes:
What happens when APFS writes a file to disk?
When APFS writes a file to disk, it examines the file, runs it through a mathematical formula that generates a shorter string that matches the file, and writes that to disk as well. When APFS reads data, it compares the data to the checksum on disk and verifies it matches.