Apple Fusion Drive
October 25, 2012

REVIEW: Apple’s New Fusion Drive

Michael Harper for — Your Universe Online

Among the surprises Tim Cook and Phil Schiller launched into the world during Tuesday´s Apple event was one small, seemingly innocuous detail called Fusion Drive.

As Schiller described it, this new drive (available in the new iMacs and Mac Minis) was simply an alchemy of flash and physical disks resulting in a perfect mix of speed and storage. The way he had described it, it was easy to interpret Fusion Drive as little more than Apple´s cutesy branding on a hybrid drive, which also pairs together SSD and HDD in one package.

As Tuesday´s event was focused on new Macs and iPads instead of geeky new technologies, Schiller only briefly mentioned the highlights of Fusion Drive before moving on to his next point, leaving many to wonder what exactly Fusion Drive really is.

With the dust settling, Apple has finally released some more information (though not much) about this new technology, revealing that this new drive might be less of a hybrid than originally thought.

Hybrid drives, like Seagate´s Momentus XT line seem to offer a bit of Nirvana to users who want both speed and storage. Ask any MacBook Air or Retina´d MacBook Pro owner: SSD is the way to go if speed is what you´re after. However, these drives remain expensive and while you can find sizes comparable to traditional spinning drives, there are few who are willing to pay the price. Terabyte hard drives are relatively inexpensive these days. An entry-level 1 TB drive can easily be found for under $100, and while real estate can be found on the cheap, these drives aren´t as zippy as many would like. Hybrid drives combine these two, relegating the most used data to the quicker SSD and the more long-term storage solutions to the HDD.

One key difference between Seagate´s hybrid drive and Fusion Drive is instantly noticeable: Apple´s drive comes with 128 GB of flash storage (or SSD) and either 1 or 3 terabytes. Seagate´s hybrid drives offer much smaller storage solutions, just 4GB paired with a 500 GB HDD or 8 GB paired with a 750 GB HDD model. This specific drive only offers enough flash memory to store a few applications and files, whereas Apple´s Flash Drive offers enough flash to store OS X as well as all applications and more, including those most-used files. According to Schiller, Mountain Lion has been built with these Fusion Drives in mind, capable of learning which files and applications are most used and moving them back and forth between the two drives. If, for instance, a user works in Logic more frequently than they work in Garageband, Mountain Lion will move Garageband over to the HDD. In true Apple fashion, the user sees only one hard drive rather than be presented with a portioned drive and doesn´t need to worry about deciding where their applications and files should go. Mountain Lion simply takes care of it all.

In order for other hybrid drives (such as Seagate´s offerings) to get flash-like speed from a larger spinning disk, a caching solution is used. In other words, these hybrid drives store a copy of the most frequently used data on the flash side and store original copies on the spinning side.

According to Stephen Foskett, Apple´s fusion drive looks to be less of a caching system, wherein files are duplicated, and more of a tiered solution. “Fusion drive “fuses” an SSD and HDD into “one logical volume” and moves files between them based on access,” writes Foskett in his blog.

“It is pre-loaded with the default Mac OS X install and moves data over time between both separate units.”

Apple has also posted an FAQ about Fusion Drive on their Web site, mentioning that users can add a partition to Fusion Drive, though the partition then becomes a separate entity and  will be left up to the user to manage.

All told, Apple´s Fusion Drive appears to take the benefits of a hybrid solution and pairs it with sophisticated software to bring near-flash speeds to a large storage setup, a clever little tweak that newer iMac and Mac Mini users may never notice unless they switch to another machine.