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Apple Fusion Drive – What is it and what the *#%@ do we do with it? [CONFIRMED]

Apple Fusion Drive

Again, Apple Fusion Drive is fundamentally different. With Fusion Drive – driven by OSX itself, data is moved from the HDD to the SSD when it’s accessed more often, and moved back to the HDD when not. This way, those every-day-use applications are super fast and apps that are there ‘Just in case’, are available at HDD speeds.

So is it all good?

Well, we don’t know. It’s not a new technology, but it is the first time it’s applied to consumer level electronics. In a RAID or BeyondRAID setup, there’s always built-in data protection. When one disk fails, and is replaced, data is rebuilt using the remainder of the array. With Fusion Drive; when one drive failed; it’s over. Time will tell if Time Machine offers ample protection.

So how about a real-world example?

I have my MBP set-up with 750 GB of harddisk space and a 256 GB SSD. This is done by removing the optical drive, moving the HDD to the optical-drive-space using a bracket and placing the SSD in the HDD spot. But instead of choosing where to put the data, sim-linking back and forth to allow software to run transparently, I was pleasantly surprised when Apple announced FusionDrive and after a few weeks of googling and waiting, the answer was presented.

I ordered myself a LaCie Rugged ThunderBolt hard disk, an ugly-orange, bus-powered (industry first!), 1 TB harddisk. Backed-up my system to it (if you remember; I had two separate volumes, one SSD, one HDD). All symlinks to the HDD needed to be removed and data moved to the original location. That took about 2 hours (thank God for Thunderbolt otherwise I would have had to wait about 7 hours over USB). Then set-up the Fusion Drive as described below, then reinstalled OSX from the recovery; took 2 hours because of slow internet. Yes, I know, I should have realised earlier that my OSX 10.8.0 USB drive would not recognise the volume, its 10.8.2 and up!!. Finally, after installing, copy back the data using the Migration Tool (which is slow of it’s own, but it did the job in 3.5 hours.)

Setting up Fusion Drive with an after-market SSD

With Mountain Lion 10.8.2 (and up, presumably) FusionDrive can be used on ANY Mac with two drives. Apparently the only thing to do is to create a logical volume across those drives. This video explains it quite clearly (this is NOT my video and I am in no way responsible for it’s content).

The commands used in this video are;

  1. Read the disk identifiers
Shell commanddiskutil list

This will create output like this;

Shell output (download file)/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *750.2 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS HDD                     749.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *240.1 GB   disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                  Apple_HFS Macintosh HD            239.0 GB   disk1s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3

Note the identifiers of the two main drives. In my case disk0 and disk1

  1. Create the logical volume
Shell commanddiskutil cs create Fusion disk0 disk1

The disk order is (probably) important; SSD first, HDD second. Also; ‘Fusion’ is the LV name, this could be any name, I called mine “FusionDrive”. I don’t have example output from my own system, but here’s some example I found on the web;

Shell output (download file)Started CoreStorage operation
Unmounting disk1
Repartitioning disk1
Unmounting disk
Creating the partition map
Rediscovering disk1
Adding disk1s2 to Logical Volume Group
Unmounting disk7
Repartitioning disk7
Unmounting disk
Creating the partition map
Rediscovering disk7
Adding disk7s2 to Logical Volume Group
Creating Core Storage Logical Volume Group
Switching disk1s2 to Core Storage
Switching disk7s2 to Core Storage
Waiting for Logical Volume Group to appear
Discovered new Logical Volume Group "DE85044F-EADA-4F26-93B7-8CD0ADF006EC"
Core Storage LVG UUID: DE85044F-EADA-4F26-93B7-8CD0ADF006EC
Finished CoreStorage operation
  1. Create the filesystem.
Shell commanddiskutil coreStorage createVolume DE85044F-EADA-4F26-93B7-8CD0ADF006EC jhfs+ "Macintosh Fusion" 300g

Now, before just copying and pasting this, please note the variables;
first, the VolumeUUID, copy this from the output of the previous command.
second, the size. Not sure why the person in the video chose 300g while his total storage would approximate 310g. According to the manual, we can input a percentage. So why not state 100%?? Also, why the ambiguous instructions? the command ‘coreStorage’ and ‘cs’ are the same, so just choose one and use it. I used this:

Shell commanddiskutil cs createVolume DE85044F-EADA-4F26-93B7-8CD0ADF006EC jhfs+ "Macintosh HD" 100%

Now, we are done!

Final notes:

  1. This WILL destroy ANY and ALL information on both drives. BACKUP FIRST!
  2. This will have to be done from the installer (create a flash drive installer or use the recovery mode) or booted from a USB, FireWire or Thunderbolt hard drive.

Right now I’m the proud user of a Fusion Drive. Now the main question, other than my eyes telling me it’s fast; how do I know the usage of both drives…. That’s the next step; getting statistics… :)

Thanks for reading :)

Author: Remon Pel

WebDeveloper though not WebDesigner

6 thoughts on “Apple Fusion Drive – What is it and what the *#%@ do we do with it? [CONFIRMED]”

  1. Well, this weekend i achieved a working Fusion drive on my “old” Imac (late 2009). I replaced the internal HD with a larger disk, replaced the optical drive with a 128GB SSD.
    Did the software configuration, installed TRIM support (needed for aftermarket SSD’s) and my bootup time is now 20 seconds !!!!!
    Fusion drive rocks ! (and can work in older imacs)
    All frequently used apps start very fast.

  2. The software config was the most easy part. This went perfect like in the video. The hardware part is the most difficult in an Imac.
    After a week working with a Fusion Drive, everything else is slow :)
    After the official warranty period i will do the same upgrade to my macbook.

  3. In your post you mention that Fusion Drive is file-based. In fact, all currently available data indicates that it is actually a block-based technology, only copying the most used data on a block by block basis. This theoretically has significant ramifications for performance, security, and reliability.

    1. You are absolutely right about FD being a block-based technology, but I think you are wrong about the ramifications for performance, security and reliability.
      Reliability: this is no more reliable or unreliable than a Raid 0 (striping) setup.
      Security: the security of any filesystem is OS based, this is no different. I can choose to do full-system-encryption on a FD so a complete set of a FD-“array” is secure, and as any striped volume setup, without the other, the one is useless. Sure you can get bits and pieces, but that’s always the case.
      Finally: performance: Well, no SSD part is slower than some SSD part and if you need ALL of the file often, then ALL of the file will be on the SSD. No problem there.

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