When decent, somewhat affordable, client focused solid state drives first came on the scene in 2008 the technology was magical. I called the original X25-M the best upgrade you could do for your system (admittedly I threw in the caveat that I’d like to see > 100GB and at a better price than $600). Although NAND and SSD pricing have both matured handsomely over time, there’s still the fact that mechanical storage is an order of magnitude cheaper.

The solution I’ve always advocated was a manual combination of SSD and HDD technologies. Buy a big enough SSD to house your OS, applications and maybe even a game or two, and put everything else on a RAID-1 array of hard drives. This approach works quite well in a desktop, but you have to be ok with manually managing where your files go.

I was always curious about how OEMs would handle this problem, since educating the masses on having to only put large, infrequently used files on one drive with everything else on another didn’t seem like a good idea. With its 6-series chipsets Intel introduced its Smart Response Technology, along with a special 20GB SLC SSD designed to act as a cache for a single hard drive or a bunch in an array.

Since then we’ve seen other SSD caching solutions come forward that didn’t have Intel’s chipset requirements. However most of these solutions were paired with really cheap, really small and really bad mSATA SSDs. More recently, OEMs have been partnering with SSD caching vendors to barely meet the minimum requirements for Ultrabook certification. In general, the experience is pretty bad.

Hard drive makers are working on the same problem, but are trying to fix it by adding a (very) small amount of NAND onto their mechanical drives. Once again this usually results in a faster hard drive experience, rather than an approximation of the SSD experience.

Typically this is the way to deal with hiding latency the lower you get in the memory hierarchy. Toss a small amount of faster memory between two levels and call it a day. Unlike adding a level 3 cache to a CPU however, NAND storage devices already exist in sizes large enough to house all of your data. It’s the equivalent of having to stick with an 8MB L3 cache when for a few hundred dollars more you could have 16GB. Once you’ve tasted the latter, the former seems like a pointless compromise.

Apple was among the first OEMs to realize the futility of the tradeoff. All of its mainstream mobile devices are NAND-only (iPhone, iPad and MacBook Air). More recently, Apple started migrating even its professional notebooks over to an SSD-only setup (MacBook Pro with Retina Display). Apple does have the luxury of not competing at lower price points for its Macs, which definitely makes dropping hard drives an easier thing to accomplish. Even so, out of the 6 distinct Macs that Apple ships today (MBA, rMBP, MBP, Mac mini, iMac and Mac Pro), only two of them ship without any hard drive option by default. The rest come with good old fashioned mechanical storage.

Moving something like the iMac to a solid state configuration is a bit tougher to pull off. While notebook users (especially anyone using an ultraportable) are already used to not having multiple terabytes of storage at their disposal, someone replacing a desktop isn’t necessarily well suited for the same.

Apple’s solution to the problem is, at a high level, no different than all of the PC OEMs who have tried hybrid SSD/HDD solutions in the past. The difference is in the size of the SSD component of the solution, and the software layer.

Meet Fusion Drive
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  • name99 - Friday, January 18, 2013 - link

    As compared to all those other tablets out there with 128 and 256GB of storage? Like uuh, huh, wait, the names will come to me...

    When EVERYONE is doing things a certain way, not just Apple, it may be worth asking if there are other issues going on here (limited manufacturing capacity and exploding demand, for one) rather than immediately assuming Apple is out to screw you.
    Reply
  • Death666Angel - Friday, January 18, 2013 - link

    Tons of Archos stuff, Samsung XE700, Gigabyte and Dell tablets etc. have >120GB storage. Reply
  • name99 - Friday, January 18, 2013 - link

    So in other words the tablets that are trying to be laptop replacements, and that have to cope with the massive footprint of Windows 8.

    You may consider this to be proof against my point; I don't.
    Reply
  • Hrel - Friday, January 18, 2013 - link

    "You can create Boot Camp or other additional partitions on a Fusion Drive, however these partitions will reside on the HDD portion exclusively."

    So you CAN create a Boot Camp partition on a Fusion Drive, it just won't utilize the SSD portion of that fusion drive at all. Or am I not understanding you?
    Reply
  • Hrel - Friday, January 18, 2013 - link

    *facepalm, I read "you can't create..." nm me... whistle whistle whistle Reply
  • Shadowmaster625 - Friday, January 18, 2013 - link

    May as well take that $400 to downtown detroit...

    Seriously though why in blazes are HDD manufacturers having such a hard time with this. How hard is it just to throw 4GB of SLC onto the little circuit board of a 1TB HDD? Yes, all you need is 4GB. The controller simply needs to perform a very simple algorithm... If the file you are writing is greater than 4MB in size, write directly to the HDD. It is a large sequential write and thus HDD performance will be adequate. If its a small write (< 4MB), write that to the SLC cache. That one tiny little optimization will get you 90% of the performance of a Vertex 4. (Depending on the bandwidth of this 4GB of SLC of course). But really it doesnt need to be as fast as a vertex 4. It just needs to be in that ballpark, for small random I/O. Large sequential I/O can just skip the NAND altogether.
    Reply
  • Ben90 - Friday, January 18, 2013 - link

    Lol, stupid. System32 and SysWOW64 would fill your NAND on installation. Reply
  • Hrel - Friday, January 18, 2013 - link

    Those entire folders wouldn't go on the NAND, they'd go on the HDD. Read the article on here about the MomentusXT from Seagate. Reply
  • Hrel - Friday, January 18, 2013 - link

    found it for you http://www.anandtech.com/show/5160/seagate-2nd-gen... Reply
  • name99 - Friday, January 18, 2013 - link

    Yeah, and USING Momentus XT sucks. The experience is horribly uneven.
    Enough stuff comes up fast that you get used to that, but enough stuff comes up slowly that it's REALLY noticeable because you're used to the occasional bursts of speed.

    I've used Momentus, I've used Fusion. There is no comparison.

    In fact (true story) after I replaced the broken HD in a friend's MacBook Pro with a Momentus she told me a week later that she thought the computer was still broken because it seemed to behave so strangely, sometimes feeling really fast, then a little later feeling so slow.

    Now, if Momentus were kitted out with
    - 64GB (maybe even just 32GB) of
    - FAST flash (not the cheap crap used in USB thumb drives) AND
    - cached writes
    it might work well. But that's not the product that Seagate is selling.
    Reply

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