What Exactly Is The Fusion Drive?

What Exactly Is The Fusion Drive?

One of the coolest things Apple announced yesterday was the Fusion Drive option for the new Mac Mini and iMac – but what exactly is it? Described as the combination of an SSD and a traditional HDD, Ars Technica has gone into more detail into how it might work, and it’s some interesting stuff.

As it explains, more than likely Apple used its Core Storage volume manager, part of Lion/Mountain Lion, which allows the OS to recognise two drives as one and transfer data between accordingly.

Ars Technica:

 Auto-tiering also includes the ability to take data that is no longer in demand, or no longer “hot” and demote it down off of fast disk and onto slower stuff. In this way, a file that doesn’t get accessed very often might be stored on slow SATA disks, but if a hundred people need to open it repeatedly over a short period of time, it will get pulled up and kept on SSD until it’s not needed anymore.

The above system is different to Intel’s Smart Technology, in that while the latter only mirrors the files to the SSD or caches them, Fusion Drive actually transfers the files, so much better performance should be expected.

Dave Hamilton at MacObserver also did some digging, and came up with some apt observations:

In a nutshell, Fusion Drive combines TWO drives, a solid state drive (SSD) and a mechanical drive. Apple’s initial incarnation puts a 128GB SSD in with either a 1TB or a 3TB mechanical drive. This is not a simple RAID, however, as 100% of the “magic” is done within OS X itself. What Fusion Drive does is it watches what files and applications you run most regularly and it moves them to the SSD. It will also take stuff that you aren’t using all that often and moves it to the mechanical drive.

Fusion Drive is definitely the thing that stood out for me at yesterday’s event, and I’m really trying to resist the temptation of buying a Mac mini with one installed.

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