Fusion Drive. A single drive?

iHateMacs

macrumors 6502a
Original poster
Aug 13, 2008
651
24
Coventry, UK
Is my 3TB fusion drive an all in one drive that contains a HDD and a SSD or is it only "one drive" because the iMac treats a 3TB HDD and a 128GB SSD as one drive but in reality they are separate devices?
 

marzer

macrumors 65816
Nov 14, 2009
1,331
45
Colorado
Is my 3TB fusion drive an all in one drive that contains a HDD and a SSD or is it only "one drive" because the iMac treats a 3TB HDD and a 128GB SSD as one drive but in reality they are separate devices?
The latter. A fusion drive is made up of two devices, a 128GB SSD and a 3TB HDD. The operating system (a subsystem known as corestorage) creates a single logical volume from the two physical devices.
 

marzer

macrumors 65816
Nov 14, 2009
1,331
45
Colorado
Yep, this - and I'd also note that it is possible to split the fusion drive into 2 separate volumes if you're so inclined.

http://www.macworld.com/article/2015664/how-to-split-up-a-fusion-drive.html
Yup. That simply deletes the corestorage logical volume leaving the drives addressable as two separate physical devices.

For some Fusion "fun" :D, follow the discussion in this thread. I've added multiple partitions (beyond the 2 permitted by the GUI version of Disk Utilty) or resized partitions in a Fusion configuration without losing the existing data.
 
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