A Month with Apple's Fusion Drive
by Anand Lal Shimpi on January 18, 2013 9:30 AM EST- Posted in
- Storage
- Mac
- SSDs
- Apple
- SSD Caching
- Fusion Drive
Final Words
For the first time since late 2008, I went back to using a machine where a hard drive was a part of my primary storage - and I didn’t hate it. Apple’s Fusion Drive is probably the best hybrid SSD/HDD solution I’ve ever used, and it didn’t take rocket science to get here. All it took was combining a good SSD controller (Samsung’s PM830), with a large amount of NAND (128GB) and some very aggressive/intelligent software (Apple’s Core Storage LVM). Fusion Drive may not be fundamentally new, but it’s certainly the right way to do hybrid storage if you’re going to do it.
It seems that Fusion Drive is really made for the user who doesn't necessarily have a ton of applications/data, but does have a reasonable sized media collection. For that user, Fusion Drive should be a reasonable approximation of a well managed SSD/HDD setup with your big media files going to the HDD and everything that you launch frequently living on the SSD. I’m always going to ask for a larger cache, but I do believe that 128GB is a good size for most client workloads and usage models today. For me in particular I’d probably need a 256GB cache for Fusion Drive to win me over, but I understand that I’m not necessarily the target market here.
The real question is whether or not it’s worth it. I’m personally a much bigger fan of going all solid state and manually segmenting your large media files onto HDD arrays, but perhaps that’s me being set in my ways (or just me being right, not sure which one). Fusion Drive doesn’t do anything to mitigate the likelihood that a hard drive will likely fail sooner than a good SSD, whereas if you go with an internal SSD and external (Thunderbolt or USB 3.0) HDD RAID array you can control your destiny a bit better. Unfortunately, in situations where Fusion Drive is a choice, you don’t often have that flexibility.
On the iMac, Apple limits your options quite a bit. You can either buy a hard drive or the Fusion Drive on the 21.5-inch model, there’s no standalone SSD option. There the choice is a no-brainer. If you’re not going to buy your own SSD and replace the internal HDD with it (or try to see if OWC’s rMBP SSD fits), then the Fusion Drive is absolutely right choice. You’re paying handsomely for the right ($250 for 128GB of NAND is very 2011), but if you’re not willing to crack open the iMac case this is really the only way to go.
For the 27-inch iMac the decision is similarly difficult. Apple does offer a standalone SSD option, but it’s for a 768GB model that will set you back $1300. All of the sudden that $250 Fusion Drive upgrade sounds a lot more reasonable.
On the Mac mini side the decision is far simpler. The Fusion Drive is only available on the $799 configuration (for $250) but so is a 256GB SSD upgrade for $300. As long as you’re ok with using an external hard drive for mass storage, here I’d go for the big standalone SSD. The usual caveat applies: this is only true if you’re not interested in cracking open the mini yourself and using a 3rd party SSD.
To make things simpler, I made bold the options I'd choose given Apple's current lineup in the table below. Note that this is still assuming you're not going down the DIY route (if you do go down that path, buy the biggest SSD you can find and rely on some external mass storage for everything else):
| Fusion Drive Options | |||
| Mac mini (2012) | 21.5-inch iMac (2012) | 27-inch iMac (2012) | |
| Base System Cost | $799 | $1299/$1499 | $1799/$1999 |
| 1TB Fusion Drive | +$250 | +$250 | +$250 |
| 3TB Fusion Drive | - | - | +$400 |
| Largest Standalone SSD |
256GB (+$300) |
- |
768GB (+$1300) |
I am curious to see how long of a roadmap Fusion Drive has ahead of it. Will NAND get cheap/large enough that even the iMac can move to it exclusively? Or will we end up with systems that have more than enough NAND to easily store everything but large media files for even the most demanding of power users? In less than a year Apple could double the size of the NAND used in Fusion Drive at no real change to cost. I suspect another doubling beyond that would be necessary to really make Fusion Drive a one size fits all, but then we're talking ~2 years out at this point and I don't know how static everyone's usage models will remain over that period of time. Go out even further in time, to the post-NAND era and there are some really revolutionary things that can happen to the memory hierarchy altogether...
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EnzoFX - Saturday, January 19, 2013 - link
Yes, exactly. This is the point of computers. It always bothers me when self-proclaimed experts come on tech sites dismissing anything of the sort. I can imagine them saying " Well just do RAID, or just manage the files yourself" and then stating that such a solution as this as unnecessary, when they clearly don't understand the point. They only work to slow such efforts down.name99 - Saturday, January 19, 2013 - link
If your friend has a mac, and if they can borrow enough temporary storage (to copy and hold the files while you make the change over), what I would recommend is that they stripe their 3 HDs together as a single volume. This can be done easily enough using the Disk Utility GUI.(Honestly they should have enough temporary storage anyway, in the form of Time Machine backup).
This will give a single volume (less moving around from one place to another) with 3x the bandwidth (as long as each hard drive is connected to a distinct USB or FW port).
[If the drives are of different sizes, and you don't want to waste the extra space, it is still possible to use them this way, but you will need to use the command line. Assume you have two drives, one of 300GB, one of 400GB --- the extension to more drives is obvious.
You partition the 400GB drive as a 300GB and 100GB partition.
You then
(a) create a striped RAID from the 300GB drive and the 300GB partition
(b) convert the 100GB partition to a (single-drive) concatenated RAID volume [this step is not obviously necessary but is key]
(c) create a concatenated volume from the volume created in (a) and that created in (b).
This will give you 600GB of striped storage, plus 100GB at the end of slower non-striped storage. Can't complain.]
Not a perfect solution, but a substantial improvement on the situation right now.
I don't know the state of the art for SW RAID built into Windows so I can't comment on that.
guidryp - Friday, January 18, 2013 - link
Really this seems like a solution for the lazy or technically naive.Manually managing your SSD/HD resources allows you to speed up based exactly on your own priorities, instead of having some software guessing and making a bunch of unnecessary copies to/from the SSD/HD.
You get faster performance of pure SSD where you want it. Less hiccups from background reorganization, and less unnecessary stressing of the SSD.
Also it isn't exactly difficult to manage manually. Use the SSD for your main OS/Application drive and whatever else you deem important for speed up.
zlandar - Friday, January 18, 2013 - link
"Really this seems like a solution for the lazy or technically naive."If everyone was technologically literate spam wouldn't exist and computer companies wouldn't need customer service for stupid questions.
jeffkibuule - Friday, January 18, 2013 - link
Aren't a lot of solutions built for the technologically naive?NCM - Friday, January 18, 2013 - link
Apple's principal market, especially for the iMac, is to home and small business users. Once again dragging out the familiar, but still applicable, automotive metaphor, I'll point out that most people don't want to work on their cars. They just want to drive reliably to wherever they're going. That's the need that Apple's FD addresses, and it seems to do so rather well.Sure, the price adder is a bit higher than one might hope, but probably not so much that it'll frighten away prospective buyers.
Interestingly though, it lost our sale. I was ready to order another iMac with a 256GB SSD and a 1TB HD for the office. We keep most of the files on the server, but a 128GB SSD application/boot drive is a bit tight. However a 256GB SSD is just right, allowing plenty of free space to maintain SSD performance. The additional 1TB HD is then repurposed for local Time machine backup.
But that's not an option for the new iMac, which offers only HD or FD. And I'm not about to make a risky and warranty busting expedition into its innards in order to roll my own SSD solution (although my own MacBook Pro has a self-installed 512GB SSD).
Instead I ordered up a 256GB SSD Mac mini, plus what turned out to be a very nice 24" 16:10 IPS monitor from HP. Although I would have preferred the all-in-one iMac solution for a cleaner installation without gratuitously trailing cables, the Mac mini with SSD, i7 and 8GB RAM options is fast and effective.
ThreeDee912 - Friday, January 18, 2013 - link
Wasn't this the kind of thing said about virtual memory in the 60's and 70's? Some people back then thought manually managing the location of everything in memory would make things more efficient, until some guys at IBM (or was it Bell Labs?) showed you saved heck of a lot more time letting the machine do it instead of trying to move things around yourself.This Fusion Drive really does reminds me of virtual memory. RAM and HDD mapped in a way so it appears as a single type of memory. Most stuff gets placed into RAM first, some stuff spills over onto the HDD, and stuff gets copied back and forth depending on how frequently it's used. The fast RAM is first priority, but there's the HDD as kind of a backup.
It's a bit different from a caching setup, where the computer has to "guess" a bit more about what should really be on the SSD. It's like the HDD is priority here, while the SSD is secondary.
And just like with virtual memory, none of this would matter if you had a huge amount of RAM or a very large SSD.
web2dot0 - Saturday, January 19, 2013 - link
Great comment ThreeDee9. Someone with a rational mind.To all those "experts" who claim that it's better to manage it yourself, you can also write every program in ASM. It'll be fast and small, but I'll be done with the project in 1/10 the time. The point is .... the product is not meant to provide "absolutely the best possible configuration". It's meant to be best all around solution.
If you guys still don't get it. Well, I guess all these years in the education didn't really help you because logical people think rationally.
psyq321 - Monday, January 21, 2013 - link
Hmm... is it just me who finds it slightly disturbing that we are comparing memory management (and, in some posts later, C vs. assembly coding) with the decision on how to organize documents/files?I would say that the intellectual investment is not really to compare.
Which does not mean that I have anything against SSD caching solutions - on the contrary, I see nothing wrong with ability to transparently manage the optimal location for the content.
TrackSmart - Friday, January 18, 2013 - link
A month ago, I would have said the same thing, but see my other post to understand why more people need this than you think. The proportion of people who can handle manually segregating their files is much, much smaller than most of us realize. I have three systems setup with both an SSD and a HDD and have no troubles. But we are a tiny, tiny minority of users.