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Fusion Drive support for existing SSD + HDD combos?

C

CausticPuppy

macrumors 68000
Original poster
May 1, 2012
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Since I've been reading that the "fusion drive" is actually two drives (hence the reason it's not available in the classic MBP models which can only fit one drive), and relies on automated tiered storage.... it seems logical to conclude there should be a way to enable the same ATS on any Mac that has both an SSD and HDD.

I've installed the OS and programs on my SSD manually, and relocated data to my HDD (again manually) which requires changing a lot of default folders and even creating symlinks in order to get things like iPod Photo Cache and SteamApps onto the second drive.

On the other hand, I always know where everything is...
 
Can´t wait to get this working with my HDD+SSD configuration!

Very interested to this topic, hope that someone finds a way to use Apple´s logical volume manager Core Storage with separate SSD and HDD drives for tiering data and drives to be seen as one logical drive.

At this time I´m using SSD for OS and programs (with ODD/HDD adapter) and HDD for data storage on my Macbook Pro. Luckily Mountain Lion update fixed some problems with folder rights and dead icons in finder. Maybe with this fusion kind of technic OS would be even faster for example with aperture, imovie and iphoto.

So if anyone hears any solution or even rumour about this, please post here! I´m quite sure there is many other users thinking of taking advantage of this great application.

:apple:
 
Fusion drive is not two drives, it is one "hybrid" drive that combines a hard drive and a smaller flash drive for most used applications... It is not a new concept, it is something like Segate momentus.
 
borostef said:
Fusion drive is not two drives, it is one "hybrid" drive that combines a hard drive and a smaller flash drive for most used applications... It is not a new concept, it is something like Segate momentus.
Click to expand...

Wrong, it is two physical pieces of hardware - one with traditional spinning platters, and the other with Flash. It is then Software (whether it's in the OS or in the Firmware remains to be seen) that manages the storage of data between the two devices.

We don't yet know whether the new Mini uses a 2.5" SATA SSD for it's Flash, or if it's "blade style" like the MBA/rMBP.

The other question is whether they've used MLC like normal SSDs, or SLC due to intensive use for caching...
 
So, what I want to know...

if I have a 2011 Mac Mini with a 500GB HDD in it now...

could I somehow upgrade and add an SSD... and then be able to use "Fusion drive"???

:confused:
 
borostef said:
It is one drive that combines the two technologies...
Look up Seagate Momentus.
Click to expand...
Yes that is how the momentous does it.
Apple is accomplishing the same thing BUT having two separate HDs, one flash and one 5400rpm, using software/firmware to join them into one volume.
 
nolem said:
Yes that is how the momentous does it.
Apple is accomplishing the same thing BUT having two separate HDs, one flash and one 5400rpm, using software/firmware to join them into one volume.
Click to expand...

Yep, the iMac / Mac mini Fusion Drive are separate SSD and hard drive. Momentus XT etc hybrid drives have about 8GB flash as a cache memory, not storage. Fusion Drive has 128GB storage for the OS and frequently used stuff and uses part of the SSD as cache.
 
Ok. Two different drives which are treated as one? Is that it? Then I got a question that will determine if I go for the 1TB Fusion Drive or the 256GB SSD...

Imagine you have a 10GB file divided in 100 RARs. Unraring it in a regular drive will take A LOT longer than doing it in a SSD. What about these Fusion Drives? Will files being used be in the SSD and then moved to the HDD as soon as you stop using them?

Another scenario: You got a 25GB video file you'd like to make a copy of in your drive for editing purposes. Will it copy it at SSD speeds or just regular HDD speeds?

Hope someone can answer this!
 
dasx said:
Ok. Two different drives which are treated as one? Is that it? Then I got a question that will determine if I go for the 1TB Fusion Drive or the 256GB SSD...

Imagine you have a 10GB file divided in 100 RARs. Unraring it in a regular drive will take A LOT longer than doing it in a SSD. What about these Fusion Drives? Will files being used be in the SSD and then moved to the HDD as soon as you stop using them?

Another scenario: You got a 25GB video file you'd like to make a copy of in your drive for editing purposes. Will it copy it at SSD speeds or just regular HDD speeds?

Hope someone can answer this!
Click to expand...

Nobody can answer that until they get a Fusion Drive in hand and find out.
 
Caching... an old hat in the PC world..

To answer your question, here is my theory:

I think apple has finally adapted the industry known caching method which was first seen at Asus a full year ago. For the Mac Pro crowd its already available. For more information have a short look here:

http://www.barefeats.com/hard148.html#sister

Since apple would need an additional controller to have something really good, I don`t think its completely software based. If this is the case it will also answer the question if you can upgrade an older mac with FusionDrive: The answer is NO! This is my prediction.

The reason it is not a hybrid drive like the Momentus XT, is the unusual size it comes in. They offer up to a 3TB Fusion drive in the iMac, hence this will not be a hybrid in my opinion. Otherwise the Momentus XT would be available in such a size which is not the case. But hey - you never know..
 
Data tiering!!

Fusion is not caching, its data tiering. Two drives that the OS manages to keep OS/[some or all] apps and frequently used data on the SSD, larger and less frequent access data on the HDD. I wouldn't be surprised if the User folder by default resides on the HDD and the Application folder by default resides on the SSD.

Any HDD to the SSD caching (if any) will probably be a relatively small OS managed intermediary caching of HDD read/write. As a second level cache to the already exisitng drive caching that occurs in RAM (whether HDD or SSD).

One significant advantage to data tiering will be memory paging, given all OS operations are contained to the SSD. This is a good future proofing to something like the new 21" iMac that has limited memory expansion.
 
If this really works how it's been told and they indeed are two separate drives I wonder how long it'll take for a tweak to come up which lets you make a folder reside only in the SSD or the HDD.

Would be nice.
 
Fusion Drive is a desktop implementation of Automated Tiered Storage that has been a data center tool for decades.

http://en.wikipedia.org/wiki/Automated_Tiered_Storage

It will be implemented in Core Storage.
http://blog.fosketts.net/2011/08/04/mac-osx-lion-corestorage-volume-manager/

http://arstechnica.com/information-technology/2012/10/apple-fusion-drive-wait-what-how-does-this-work/

----------

BTW - here is additional info from Anandtech.

It's 2 physical devices. One SSD and one HDD.

http://www.anandtech.com/show/6406/understanding-apples-fusion-drive
 
yeah some pc mobos do it with an msata ssd and a 2tb or 3 tb 3.5 inch hdd.

I had one setup in my asus build.


It is okay but ssds got cheaper and I just put in 2 ssds. a 256gb msata and a 512gb ssd but from crucial. I then turned off the option on my asus board. Knowing apple it may be restricted like trim was. 250 is an awful lot. your already have the 1tb hdd and are only adding a 128gb ssd for 250 more.
 
MatthewAMEL said:
Fusion Drive is a desktop implementation of Automated Tiered Storage that has been a data center tool for decades.

http://en.wikipedia.org/wiki/Automated_Tiered_Storage

It will be implemented in Core Storage.
http://blog.fosketts.net/2011/08/04/mac-osx-lion-corestorage-volume-manager/

http://arstechnica.com/information-...le-fusion-drive-wait-what-how-does-this-work/

----------

BTW - here is additional info from Anandtech.

It's 2 physical devices. One SSD and one HDD.

http://www.anandtech.com/show/6406/understanding-apples-fusion-drive
Click to expand...

TY

And THANK YOU Anandtech for being an actual tech magazine. I was about to lose hope, googling for fusion drive and finding no real information...
 
So from the Anandtech article it sounds like this is going to work just as well and potentially better than manually creating a boot SSD + HDD.

I've done the latter before and it's not that hard - in hindsight I'd just put the system and apps on the SSD, and the user directories on the HDD. I went a bit further keeping my user directory on the SSD, and symlinking all the big folders away, like Music, Pictures, Movies. An 80GB SSD is a bit too small for this so I also had to symlink away various apps, and Application Support folders. It was a pain.

What the fusion drive does is:
- Put all system folders and files on the SSD
- Provide a 4GB write buffer for the HDD to take care of all the random small writes
- Dynamically reorganize the SSD / HDD - move frequently used files and apps to the SSD, and less frequently used ones to the HDD.

Most importantly, this is not a simple cache of the HDD. SSD and HDD are used in parallel, with the entire capacity available.

I am hoping that Apple was smart and actually pinned the entire system directory to the SSD - it's small there's no reason to move parts of that out, and it reduces the likelihood of something going wrong.

If I were to write that algorithm, I'd also just pin all large files that don't experience write access to the HDD. That would cover all media files, movies, pictures, and music.

It sounds like Apple is doing all this on a OS level so at least in theory they can make very good decisions about what to move and what not to move.

This is in comparison to BIOS based algorithms... like that Seagate Momentus, it knows nothing about your system, about OS X, and doesn't even know how HFS+ works - all it has to go by is blocks. Even with a perfect algorithm it could never work very well. And performance tests show that it's mostly a marketing gimmick, at best it's marginally faster than an average 7200 HDD.
 
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