A Month with Apple's Fusion Drive
by Anand Lal Shimpi on January 18, 2013 9:30 AM EST- Posted in
- Storage
- SSDs
- SSD Caching
- Mac
- Apple
- Fusion Drive
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.
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KitsuneKnight - Friday, January 18, 2013 - link
Currently, 10 VMs, totally approximately 130 GBs. My SSD is only 128 GB. Even if I'd sprung for a 500 GB model (which would have cost closer to $1,000 at the time), I'd have still needed a second HDD to store all my data, most of which would work fine on a traditional rust bucket, as they're not bound by the disk's transfer speed (they're bound by humans... i.e. the playback speed of music/video files).Also, for any data stored on the SSD by the fusion drive, it wouldn't just "rival" SSD speeds, it would /be/ SSD speeds.
I'm also not sure what your comment about RAM is about... Operating Systems do a very good job managing RAM, trying to keep as much of it occupied with something as possible (which includes caching files). There are extreme cases where it's less than ideal, but if you think it'd be a net-win for memory to be manually managed by the user, you're nuts.
If one of the drives fail, you'd just replace that, and then restore from a backup (which should be pretty trivial for any machine running OSX, thanks to TimeMachine's automatic backups)... the same as if a RAID 0 array failed. Same if you want to upgrade one of the drives. Reply
Death666Angel - Friday, January 18, 2013 - link
Oh and btw.: I think this is still a far better product than any Windows SSD caching I've seen. And if you can use it like the 2 people who made the first comments, great. But getting it directly from Apple makes it less appealing with the current options. ReplyEnzoFX - Saturday, January 19, 2013 - link
This. No one should want to do this manually. Everyone will have their own thresholds, but that's besides the point. Replyrobinthakur - Sunday, January 20, 2013 - link
Lol exactly! When I was a student and had loads of free time, I built my own pcs and overclocked them (Celeron 300a FTW!) but over the years, I really don't have the time anymore to tinker constantly and find myself using Macs increasingly now, booting into Windows whenever I need to use Visual Studio. Yes they are more expensive, but they are very nicely designed and powerful (assuming money is no limiter) Replymavere - Friday, January 18, 2013 - link
"The proportion of people who can handle manually segregating their files is much, much smaller than most of us realize"I agreed with your post, but it always astounds me that commenters in articles like these need occasional reminders that the real world exists, and no, people don't care about obsessive, esoteric ways to deal with technological minutiae. Reply
WaltFrench - Friday, January 18, 2013 - link
Anybody else getting a bit of déjà vu? I recently saw a rehash of the compiler-vs-assembly (or perhaps, trick-playing to work around compiler-optimization bugs); the early comment was K&P, 1976.Yes, anybody who knows what they're doing, and is willing to spend the time, can hand-tune a machine/storage system, better than a general-purpose algorithm. *I* have the combo SSD + spinner approach in my laptop, but would have saved myself MANY hours of fussing and frustration, had a good Fusion-type solution been available.
It'd be interesting to see how much time Anand thinks a person of his skill and general experience, would take to install, configure and tune a SSD+spinner combo, versus the time he'd save per month from the somewhat better results vis-à-vis a Fusion drive. As a very rough SWAG, I'll guess that the payback for an expert, heavy user is probably around 2–3 years, an up-front sunk cost that won't pay back because it'll be necessary to repeat with a NEW machine before the time. Reply
guidryp - Friday, January 18, 2013 - link
These claims about the effort in setting up SSD/HD combo are getting quite silly.There is essentially ZERO time difference into setting up SSD/HD partitioned combo vs Fusion. Your payback would be on Day 1.
The only effort is simply deciding which partition to load new material on. That decision takes what? Microseconds.
It is as simple as install OS/Apps on SSD, Media HD. Vs Install OS/Apps/Media on Fusion. The effort is essentially the same.
But that simple manual partition will perform better, create less system thrashing and less wear on all your drives. Reply
Zink - Friday, January 18, 2013 - link
But then you end up with a SSD filled up with no longer relevant data and you need to figure out how to free up space again. A combo drive takes care of that for you and keeps the SSD filled to the brim with most of the data that gets used. You can download any games, start any big video editing project, and know that you are getting 50%-100% of the benefit of the SSD without worrying about managing segregated data. With a segregated setup you end up playing games from the HDD or editing video files that are on the HDD and sometimes see 0% of the benefit of the SSD. Fusion seems like the future. ReplyKitsuneKnight - Friday, January 18, 2013 - link
If you can divide your data up as OS, Apps, and Media, and OS + Apps fits on the SSD, then sure, it's not too bad.Unfortunately, my Steam library is approximately 250 GBs... That alone would fill up most SSDs out there. And that's not even counting all my non-Steam games, which would help push most any SSD towards being totally full. If I'd bought too many recent games, it'd likely be quite a bit larger than that (AAA games seem to be ranging from 10-30 GBs these days).
Unless you sprung for a 500 GB SSD (which aren't exactly cheap, even today), you'd be having quite a pickle on your hands. Likely having to move most of the library manually to the HDD (which is a bit of a pain with Steam). Which means it's suddenly much more complicated than OS/Apps on SSD, and Media on the HDD. Especially since SSDs massively improve the load time of large games (unlike the impact it has on media).
And then there's the other examples I've already given: the artist I know that works on absurdly massive PSDs, and has many terabytes of them (what's the point of a SSD if it doesn't benefit your primary usage of a computer?), as well as my situation with VMs on my non-gaming machine (which actually has a SSD + HDD setup right now). A lot of people could probably do the divide you're talking about, but likely even more people could fit all their data in either a 128 or 256 GB SSD. Reply
name99 - Friday, January 18, 2013 - link
Then WTF are you complaining about?You can still buy an HD only mac mini and add your own USB3 SSD as boot disk.
Or you can buy a fusion mac mini and split the two drives apart.
It's not enough that things can be done your way, you ALSO want everyone else, who wants a simple solution, to have to suffer? Reply