What is Apple’s Fusion Drive?

As you may have seen during our live coverage of the Apple event earlier this week, Apple has announced a new feature called Fusion Drive for its latest iMac. Few details were released during the launch, and things were a little bit confusing and blurry for those who were asking for more details.

The idea of Fusion Drive is not new: Apple is trying to provide its users with SSD performance (most of the time) and high capacity at the same time. To do that, it uses two drives: a 128GB SSD (probably similar to the Macbook Air unit) and a mechanical disk.If using a broad definition of “hybrid drive”, Fusion Drive could fall into that category, but it would be a bit misleading to compare it with HDD/SSD drives where the SSD part is more or less a cache area for most-frequently accessed files – they are called “hybrid drives” today.

Apple Fusion Drive is not a caching mechanism, that’s why I won’t call it a “hybrid” drive. Fusion Drive is two independent disk which are bound together as one by the OS. This is for example very different from system like RAID where data is copied partially (or totally) on both drives. From what we can tell, with Fusion Drive, a file that is on the SSD is not on the HDD.

The operating system will be responsible to pick and chose which files go on which disk, based on some predefined performance pattern that Apple sees fit. The idea is quite simple: SSDs are really awesome for random accesses, while HDD are doing OK for contiguous files and huge files. Normally, this should work well on average.

There are a few details that you may want to know about:

* Backups with Time machine work as usual. Nothing new here. Time machine sees a single drive and copies the files from it.

* It is possible to create one additional partition, but it will be located on the mechanical hard drive

* It is possible to create a windows partition (Bootcamp), but not on the 3TB version at the moment.

* Fusion Drive’s features like remote system mounting work only with Mac OS 10.8.2+ (Mountain Lion)

* For additional details about Fusion Drive, we recommend checking Apple’s official FAQ page.

Hubert Nguyen
Categories: Apple
Tags: iMac, Storage