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BC2009

macrumors 68020
Jul 1, 2009
2,237
1,393
There seems to be a lot of confusion about what a Fusion drive is... The Fusion drive is software based, it is not hardware. A hybrid drive IS hardware, and is NOT what Apple's marketing department has called a Fusion Drive. The Fusion drive is a SSD & a HDD in an iMac, and at the OS level, it is picking and choosing where to store programs / data. So the title of this article is correct, if you also own a Mac, and own a SSD & HDD attached to that Mac, you can also have a "Fusion" drive (assuming Apple doesn't shut down these command line hacks). This isn't misleading at all. Will it perform the same as the Mac version? That depends on what SSD / HDD Apple is using versus what SSD / HDD YOU are using.

I have a Mid 2011 Mac Mini, with a SSD / HDD installed, and I cannot wait to try this out, I currently have my home directory on the HDD to save room, but with this setup, the OS can choose where to put everything, which is truly ideal.

I want to do this in my two iMacs. Do I need to do it from the recovery screen, open the terminal, setup the drive, and then reinstall Mac OS X and restore from time machine?

I would really appreciate you posting how your experience goes with this.

It only costs $200 to get a 120GB drive and "Data Doubler" adapter + external enclosure for the existing Super Drive of my iMac from OWC.

What's more, the local Apple-Authorized repair shop that is going to do the warranty replacement of my iMac's internal seagate drive says he would not mind hooking this up while he is in there. So this is an ideal time to setup my 2009 iMac's boot drive in a "Fusion" configuration.
 

Nunyabinez

macrumors 68000
Apr 27, 2010
1,758
2,230
Provo, UT
P.S. Physical hybrid drives suffer from usually having too small a SSD to be effective in a broad range of contexts. The "cache" size is just too small relative to the HDD storage component. That is in part driven by largely only targeting 2.5" drives at first. There isn't much empty space inside of a 2.5" drive to work with. The same space means have to do heavy writing to a limited number of flash memory modules. that usually tiggers using much more expensive SLC flash instead of mainstream MLC flash.

If Apple uses a 128GB drive with a 1TB HDD about 10% of used capacity can be on the SDD ( assuming don't fill the system to the brim. Shouldn't for a variety of reasons ). 2.5" hybird drives typically have 4GB and either capacities in the 500GB 1,000GB range. That means in the 4% range.
It is much easier to get a good sized working set in 10% than it is 4%.

The nice thing about this implementation is that one could "reconfigure" each part of the fusion drive as needed. For example, I could start off with a 128GB SSD and then switch it out for a 256GB later when I can afford it. Of course it would require a reformatting and a restore from back-up, but it gives me more flexibility as drive prices change.
 

madmaxmedia

macrumors 68030
Dec 17, 2003
2,932
42
Los Angeles, CA
This should mean that the method described could potentially be stable since it should be virtually what Apple is doing. I have a Hackintosh that I use for just this kind of tinkering but I have held off on the SSD because I didn't want to screw around with files spread across several drives. But, now I may get one and try this method since it would be invisible to me in use, but would also really speed things up.

Yeah exactly! I mean the results people have gotten so far (still early but still) really bode well for DIY. Perfect if you have a second Mac to play around with.

Don't know if you saw this other post which confirms the results:
http://www.petralli.net/2012/10/ana...macs-with-an-ssd-and-a-traditional-hard-disk/

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I hope it will work in a MacBook Pro with optibay.

I can't think of a reason why it wouldn't work...I'm thinking about the same thing!
 

leman

macrumors Core
Oct 14, 2008
19,197
19,056
What about booting from a hand-created fusion drive? Won't you need firmware support for that?
 

gnasher729

Suspended
Nov 25, 2005
17,980
5,565
Apple's implementation of Fusion Drive with a SSD and a HDD is only one way such software could be used. One could literally reverse the drives and intentionally put the slow one on the wrong end and the software would still function, albiet with crippled results.

It opens other possibilities. Doesn't have to be SSD and HD. Could be a 10,000 rpm drive and a slower drive. One possibility would be an implementation in iOS, making iDevices that have a small amount of fast+expensive flash, plus a huge amount of slow+cheap flash.
 

Nunyabinez

macrumors 68000
Apr 27, 2010
1,758
2,230
Provo, UT
Yeah exactly! I mean the results people have gotten so far (still early but still) really bode well for DIY. Perfect if you have a second Mac to play around with.

Don't know if you saw this other post which confirms the results:
http://www.petralli.net/2012/10/ana...macs-with-an-ssd-and-a-traditional-hard-disk/

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I can't think of a reason why it wouldn't work...I'm thinking about the same thing!

I think I'll give it a shot. I might wait for someone to make a GUI tool for this. I've ventured into the terminal for a few hacks, but I'm not an expert by any means. But on the other hand it doesn't look all that hard and it's not like I don't have experience recovering my Hackintosh from complete FUBAR :p.
 

tipp

macrumors regular
Sep 9, 2010
114
3
The nice thing about this implementation is that one could "reconfigure" each part of the fusion drive as needed. For example, I could start off with a 128GB SSD and then switch it out for a 256GB later when I can afford it. Of course it would require a reformatting and a restore from back-up, but it gives me more flexibility as drive prices change.

I was thinking about SSD sizes in this implementation and I'm not sure most people would need more than 128GB. We should at some point in the future have affordable 1TB+ SSDs, which would then make this solution unnecessary, but for now, I doubt most people are moving or using more than 128GB of high-use data on a regular basis. This Fusion Drive solution is specifically meant to marry the high speed of SSDs with the cheap storage space of traditional HDDs.
 

deconstruct60

macrumors G5
Mar 10, 2009
12,296
3,890
That would be a problem.

It only is perhaps a boot problem. It certainly is a target disk mode problem. ( TDM isn't going to work with ). Once the OS is running and CoreStorage loaded is probably doesn't matter much about these unsupported configs.

USB 3.0 ( or any external storage connection that is easily yanked out) is a problem in that the logical drive likely will be corrupted in an unclean dismount. Internal, SATA drives typically are yanked out while the system is running.
 

gnasher729

Suspended
Nov 25, 2005
17,980
5,565
I've been using a Seagate Momentus 500GB Hybrid drive for 2 years in my 2008 MBP after I ran out of space on the original 200GB drive. I was curious myself about how a hybrid drive would perform vs this new Fusion drive and found this article:

http://www.zdnet.com/mac-fusion-drive-pro-users-beware-7000006661/

Well, he's mouthing off about HFS+. In my many years of experience with Macs, HFS+ is absolutely rock solid. Everything he criticises is pure conjecture, with no actual evidence.
 

iGrip

macrumors 68000
Jul 1, 2010
1,626
0
Is this a stable setup? The article is very technical and doesn't really say if a non-techie could make it work safely. I notice he isn't providing any script to automate the setup process.



This sort of stuff is only for self-identifying s00pR Geek weirdos, and they are NOT Apple's preferred customer base.

Don't try this at home, or you will likely brick your new $2000 computer. It isn't worth the chance.

The last thing we need is for people to ruin a perfectly good Apple product and then tie up the Geniuses and Apple Care with their lies about "I don't know what happened - it just stopped working!" That costs money and time for the entire Apple community.

No good can come of this.
 

oculus42

macrumors 6502
Dec 9, 2002
320
6
Maine
If you store your system and applications on your SSD, and your iTunes library, your Photo libraries, your Video and Media files on your Hard Drive, there is no need for this "Fusion" system. I like the way my system works as it is, I don't want the system "moving" files between the two drives and slowing things down. My system is fast as lightning!

Correct. You and I both manually choose the location of files -- OS & Apps on SSD, data on HDD -- to try to balance performance with cost/capacity.
Fusion does the same thing.

Sure, when you go to load OmniGraffle for the first time in three years, it may have been moved to the HDD to make room for that copy of Memento you've watched fifteen times, but the goal is to free up enough of your time by not hand-organizing your files to more than make up for the occasional performance penalty.

Think of this exactly like predictive caching in processors... they monitor the activity, they use predictive logic and a history table to guess what you'll need next, but sometimes they are wrong. But a "cache miss" happens much less than a hit, and less often still as we improve the technology. The performance is miles ahead of where it would be without caching, because even hand-tweaking everything in assembly/machine code for the best performance can't compete with the amount and variety of multitasking activities your computer is performing.

Also, based on this article, it appears to wait for availability/idle on the drives to move files and not slow the user down. Yes, there has to be some small performance hit to monitor the file activity, but it's interesting to see how it works and how it evolves.

ZFS supports memory caching and cache drives to provide extreme performance for SANs and heavy load situations. While flash may be the eventual and ultimate storage solution, HDDs aren't going away soon because their cost/GB is very low.

It's an interesting time in storage.
 

InfoTime

macrumors 6502a
Jul 17, 2002
500
261
To those that think Fusion Drive is some type of special hardware I refer you to the keynote. They showed a slide of the layout of the new iMac's logic board. On the lower left they call out the SSD, which looks like chips soldered to the board or a small SSD on a card like a MacBook Air. On the upper-to-mid right you see a traditional hard drive.
 

oculus42

macrumors 6502
Dec 9, 2002
320
6
Maine
Well, he's mouthing off about HFS+. In my many years of experience with Macs, HFS+ is absolutely rock solid. Everything he criticises is pure conjecture, with no actual evidence.

The ZFS vs. HFS+ is not about the filing system so much as it is about the handling of hardware errors. ZFS can and does catch it when your hard drive flips a bit or incorrectly reads/writes one or two bits in a billion. ZFS does not suffer from "silent" data corruption. HFS+ does. If you've ever opened a JPEG and half of it is missing/corrupted, you probably experienced silent data corruption.

I know I have.
 

brand

macrumors 601
Oct 3, 2006
4,390
456
127.0.0.1
Don't try this at home, or you will likely brick your new $2000 computer. It isn't worth the chance.


This would not brick the computer since the storage drives could simply be repartitioned or replaced.

To brick a device means that the device is completely unrecoverable by any means. Using the wrong terms makes it confusing for those that barely/don't understand in the first place.
 
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Berserker-UK

macrumors regular
Jan 4, 2012
102
55
Berkshire, UK
Anyone thinking of doing this, or buying into the 'real thing', please don't forget that Fusion Drive (as a whole system, to avoid any confusion) has a lower MTBF than an SSD or HDD alone. Just like RAID 0, a failure in either drive destroys the data on both, and now you have failures of the driver to add on top.

In other words, use Time Machine!
 

gamrin

macrumors newbie
Jul 26, 2012
24
25
I don't know if anyone's mentioned this already, but one of the "minor" benefits of the actual Fusion drive (other than being a brilliant transition technology between traditional HDDs and faster SSDs) is that it takes up only one drive slot in your computer. Sure, you might be able to emulate the Fusion drive functionality using a separate SSD and HDD (and some command line trickery), but you'd have to use up two drive bays—or add an external drive—to do so.

So, the Fusion drive offers another benefit over a DIY Fusion multi-drive set up, though admittedly a minor one. That said, I ordered a Mac Mini last week with the Fusion drive. I plan on putting a separate 256 GB SSD into it and running Windows on it (mainly for light gaming) when it arrives. I appreciate having that second drive bay free.
 

gnasher729

Suspended
Nov 25, 2005
17,980
5,565
His test may have been relatively simple, but it certainly showed something interesting. I would postulate that it probably rolled out with 10.8.1 or 10.8.2. The larger question is if it operates at file-level or at the block level...

Here's how it works (it's conjecture, but it's the only model that makes sense):

Say you have a 1TB HD and 128GB SSD. That's 250 million 4KB blocks on the HD, and 32 million on the SSD. The operating system figures out which blocks a file should cover. Preferably consecutive blocks, otherwise you have fragmentation (that is what Windows defragmentation programs do, putting files into consecutive blocks).

With the fusion drive, if the OS says "this file is from block 13,000,000 to 13,000,099", that means it's on block 13,000,000 to 13,000,099 on the SSD. If the OS says "this file is from block 46,200,050 to 46,201,300", that means it's on the HD, we subtract 32 million, so it's on block 14,200,050 to 14,201,300 on the HD. If the OS says "this file is from block 31,999,960 to 32,000,050", that means the first blocks are on the SSD, and the rest on the HD. Unusual, but not actually a problem.

When you have a fragmented file (not one range of blocks, but several), that's no problem at all, and these ranges of blocks can be anywhere, on the SSD, on the HD, it doesn't matter.

Now there is some code that moves files to different places (off the SSD, or onto the SSD). It may be that this code tries to move the whole file at a time, but it doesn't really have to. And if there is normal fragmentation of files, that doesn't matter either.
 

Swift

macrumors 68000
Feb 18, 2003
1,828
964
Los Angeles
Is this really exactly the same as Apple's implementation of Fusion Drive? That wasn't made clear to me by the article.

Well, he's using the command line to implement something built in to Mountain Lion, called Core Storage. So the ability to make SSD and HDD one logical volume, the algorithms about what to transfer to the SSD and when, this is part of Core Storage. It's also very interesting that ZFS disks are recognized by the OS.
 

risotto

macrumors newbie
Apr 24, 2012
4
0
I have a 128gb ssd and a 1tb in my macbook pro. I can't wait to see if I can get this working. Also, I wonder if there are any issues with bootcamp when two drives are working in 'fusion'.

You can try following my guide I wrote up for this: here
 

tbrinkma

macrumors 68000
Apr 24, 2006
1,651
93
So it's Apple's poorly worded tech name, and the fact that I can select Fusion Drive instead of HDD, when it's already in every computer running 10.8.2, that has caused my misunderstanding.

Fusion Drive is the software tech. When I select "Fusion Drive" when configuring a MacMini what I am really selecting is a SDD and a HDD combo, not a physical item called a "Fusion Drive."

I'll rephrase my original statement, Apple misleading is misleading.

No, it's your own confusion that is misleading, the description of the Fusion Drive feature has been accurate and clear all along. When you select "Fusion Drive" when configuring a Mac mini, you are selecting an SSD & HDD *configured* as a "Fusion Drive". You misunderstood, and when confronted with a description which didn't match your understanding, you reacted by being obstinate and certain that you were correct. You then proceeded to tell someone else (who had accurately described the situation) that *he* was wrong.

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I like the idea of the FusionDrive - had it myself some years ago as a matter of fact, but who cares.

What I am interested in:
What happens if the SSD in this setup fails? (after complete re-writing to the HDD of cause) Maybe the author or anyone else could test this.
Would be a great option to beef up my 27" without the hassle of splitting my data and still have the benefits of the SSD while working.

The same thing that happens when a single disk in any other non-redundant, multi-disk bundle dies. You replace it, and restore from backups.

Fusion Drive is essentially a two-disk JBOD array with some software 'special sauce' managing which physical drive gets to handle which bits of data.
 
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