Fusion Drive: The Future of Storage

Through the MacBook Air, Apple has pioneered the everyday use of flash storage as an alternative to traditional hard drives. With the inevitable discontinuation of the pre-2012 MacBook Pros, Apple’s MacBook lineup will go completely flash-based and it looks as if the desktop Mac is going that way to… well, kind of.

At their October special event, Phil Schiller announced Fusion Drive, a new storage technology available for configurations of Apple’s late 2012 Mac Minis and iMacs. Fusing together flash and traditional storage, Apple aims to create a faster storage medium that still offers up a large capacity. In this article, we’re going to run through the basics of Fusion Drive, the technologies behind it and what it means for the future of storage on your Mac.

What is Fusion Drive?

Essentially, a Fusion Drive from Apple has two parts: a flash storage drive and a traditional, higher-capacity hard drive. To the user, these are presented as a single logical volume with no visible distinction between what is flash storage and what is the slower, more traditional medium.

Hybrid drives are nothing new but they do differ to Apple’s Fusion Drive. Hybrid drives generally work by caching items stored on a hard drive to flash storage, mirroring them for to the quicker drive for faster access. However, Fusion Drive is different because the software dynamically moves more popular content to flash storage, leaving less frequently-access data on the hard drive.

Phil Schiller explains Apple’s Fusion Drive at their October 2012 Special Event.

Fusion Drive gives users the best of both worlds by offering faster speeds but with more overall storage. Plus, among other reasons, combining the drives rather than using the flash storage as a mere mirror offers users a combined capacity of both drivers. So, a 1TB hard drive combined with Apple’s standard 128GB of flash storage means users have a total of ~1.12TB of space to use. The 128GB flash drive can be combined with a either a 1TB or 3TB hard drive at launch.

Importantly, OS X handles everything automatically. Mountain Lion can intelligently work out which files are used more often and move them to the flash storage, relegating less-used data to the slower hard drive. Of course, the operating system is stored on the flash drive too, providing fast start up times and other advantages.

What Fusion Drive Is Not

Before Fusion Drive, there was two generally popular ways of increasing drive performance. The first is the aforementioned method of caching data from a hard drive onto a flash storage medium which is similar to Fusion Drive but means that users don’t get access to the combined capacities of both drives.

An example of a Fusion Drive setup, where the OS and frequently-used apps are located on the flash storage.

The other is RAID — redundant array of independent disks — drives, combining multiple drives into a single volume. There’s multiple methods of creating RAID drives and without writing a whole article on this technology alone, there are some minor similarities to what Fusion Drive does and performance benefits achieved with such a setup.

The Future of Storage?

In notebooks, we’re slowly getting used to using lower-capacity flash storage, with Ultrabooks and machines like the MacBook Pro with Retina Display leading the charge against slower storage. As component prices go down, so will the cost to consumers. Eventually, we may reach a time where solid state storage is affordable in capacities similar to what we enjoy with more traditional means.

Flash storage has been the medium of choice for Apple’s MacBook Airs and MacBook Pros with Retina Displays.

With a lot of consumers invested in a two-machine system (such as one laptop and one desktop), the need for higher-capacity storage on a MacBook is lower than it is on desktop. We want the speed of flash storage but the capacity of a hard drive? Fusion Drive seems like the perfect solution.

Pricing and Availability

Chances are we won’t see Fusion Drive in MacBooks, especially due to the very size constraints that played a major factor in Apple opting for flash storage versus traditional hard drives in these latest designs. However, Apple’s desktop lineup for the holidays supports Fusion Drive well with all but the ageing Mac Pro having the option to configure a Fusion Drive.

The late 2012 models of Mac Mini and iMac use hard drives as their default storage option, but Fusion Drives are configurable on all models of iMac and the 2.3GHz quad-core Mac Mini. The Mac Mini and 21.5″ iMac support a Fusion Drive with a 1TB hard drive, whereas the 27″ iMac has the option for a Fusion Drive with a 3TB hard drive too.

Fusion Drive configurations are priced slightly less than the pure SSD counterparts.

Prices for Fusion Drives on the new lineup of iMacs are unavailable as they are not yet available to order. However, supported Mac Mini can be ordered with a 1TB Fusion Drive for a $250 premium. That might seem costly, but comes in at just $50 less than the option of 256GB of pure solid state storage. Although, those wanting no more than 256GB of storage might be better suited to paying the extra $50 and going pure flash.

Final Thoughts

Fusion Drive was a surprise announcement last month, alongside Apple’s insanely thin range of new iMacs. Apple is finally attempting to move flash storage, or at least the advantages of it, to the desktop. However, like when solid state storage first came to the Mac, it’s likely Fusion Drives will continue to sell at a premium but leave a few years and it might just become the standard.

Until we get to a point where pure flash storage is an affordable possibility, Apple’s Fusion Drive signals a pleasing solution in the meantime.


Add Yours
  • The Fusion drive, to me, seems to have the largest (potential) drawback of a RAID 0 setup. You double your chances for drive failure.
    Not only that, but you are also (again, potentially) reducing the lifespan of your HD by making it contingent on a SSD which typically speaking has a shorter life-span.
    Unless of course I completely misunderstand the level of dependency the two drive have on one another.

    • They are not dependent such as a RAID would be where the file would be spanned across multiple drives.

      If the HDD fails, you would lose what is on it, but not what was on the SSD.

      Of course, Time Machine would be the best option for protection. What I would love to see is the ability to manage Time Machine across a network, and even off-site. This way I can back up all my files locally while also making a safe backup remotely.

    • The MTBF of SSDs is higher than hard drives.

  • Comment removed by editor for extremely offensive language.

    • Many thanks noko for your insightful comment.

    • Fusion Drive isn’t, technically, a mere hybrid drive, though. It integrates with OS X in a way that mitigates the user’s responsibility to manage the setup.

      • Connor, I’m extremely disappointed noko’s post would be allowed to persist, let alone that you as a representative of this site would give it such undeserved respect by even responding to such a profoundly hateful post.

        (And to be clear, I’m a strong defender of free speech, and have no issue with the use of profanity to make a point – but noko’s post clearly goes beyond the line of a reputable website such as appstorm. Shame on you.)

        • As editor, I’m sorry that comment got published on the site, and have removed it now.

      • For someone who hates Mac users, he sure is in a peculiar part of the internet isn’t he?

        Comment edited by editor.

  • The vast majority of this functionality is all in the software. You can setup your own “FusionDrive” pretty easily:

    (and no, that it’s my site I’m linking to)

  • Fusion Drive is the best compromise of the need for increased speed but not at the expense of storage. Disregard those that trivialize FD. Tiered Storage has been done for years but in the Enterprise. This is a great move for consumers yet in Apple tradition the management of the tiering is drop dead simple. There is none.

  • I have a hybrid drive installed now (since the original drive failed and the hybrid was all Best Buy had in stock at the time). I don’t know exactly how it works, but I was under the impression that it was doing exactly what the Fusion Drive is supposed to do. As I understand it, all drives being managed by Mac OS have a “fast” portion where files that rarely change and are frequently used get stored, and when using a hybrid drive those files end up on the flash portion as storage space allows.

    Is this not what a Fusion Drive would do? I guess they said it would store documents too, so that wouldn’t count as a file that rarely changes… hmmm…

    …anyway, I would like to know the differences a bit more specifically.

    • Technically, a hybrid drive will make “replications” of frequent-accessed files, and keep these replications in the solid-state memory. Solid-state memory acts as a “mapping” area to the magnetic storage, not parts of total storage space. An 1T & 128G hybrid drive will give you a total space of 1T, not 1024G + 128G.

      But Fusion Drive will “move” these files between solid-state and magnetic storages. Solid-state memory IS part of total storage space. 1T & 128G means you’ll get 1024G + 128G.

      Of course Fusion Drive can provide benefits more than extra storage space. The best part of Fusion Drive is eliminating the write-back / write-through mechanism.

      Write-back and write-through are two different mechanisms generally used by “cache” approaches. Take hybrid drive for example; suppose that you’ve opened a file, and that file is cached in the solid-state memory. When you save the file and close it, what will happen next ?

      Since the “cache” will expire anytime, the hybrid drive will eventually write the new file back to magnetic storage. “Write-back” means hybrid drive will only update the replication cache in the solid-state memory, and write to magnetic storage when the cache is about to expire; and “write-through” means hybrid drive will update solid-state memory AND magnetic storage simultaneously whenever you’ve made changes to the file.

      Either way, there would be performance drop and risks of data inconsistent during updating.

      However, with Fusion Drive, there is no need for write-back or write-through at all, since there is only one instance of file exists at any given time.

      The downside of Fusion Drive is that the main CPU would take some extra effort managing files; though this would be less significant.

      • Interesting. Thanks for the explanation.

  • I am very encouraged with this newish technology.

    Back in the day, we use to move the most frequent files (boot files) to the center of the HDD as reads would be quicker. 1) less distance to the outer rings, and 2) shorter distance around the platter.

    I love the dynamic nature of this system and that OSX manages it. Having all your frequent files such as applications and system files as well as documents/images/audio/video on the SSD and moving all the infrequently accessed files to the HDD is much the same as buying a external drive and moving all your old home videos off to that drive to free up space on the local, faster drive.

    Eventually we will have RAID SSD drives coupled with large volume HDD.

  • I disagree, wait a few years until SSD becomes cheaper and with more storage potential and it should replace classic hard drives.

    • It’s possible that solid-state memory will eventually cheaper than classical hard drive, but Fusion Drive technology would still get its place.

      It’s not well known to the public, but the “SSD” term in fact can be referred to a vast varieties of different solid-state memories. For example, the multi-cell level memory is low in price, but much slower than single-cell level memory.

  • Spinning drives are going the way of the dinosaur. Flash/SSD are the way of the future. This “Fusion-Technology” seems like more of a stop gap than anything else.

  • I’m disappointed that many of the “genius”s out here are determined to find fault in everything Apple does. Instead of rejoicing at this typical Apple (i.e., simple to the user) EVOLUTIONARY offering giving us the best of both worlds, some are determined to complain. Give them a sack of gold and they would whine about the weight.

  • I may be mistaken, but this seems like a three to four year old technology (Seagate Momentus XT) with a prettier name. I may be mistaken, but I see no difference between the two, except that the seagate drive costs around $90 and this appears to cost far more. Please correct me if I am wrong.