DIY Fusion Drive - Setup recommendations?

Discussion in 'OS X Mountain Lion (10.8)' started by Heb1228, Nov 28, 2012.

  1. Heb1228 macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    I just got a 240GB SSD and a 750 GB HDD. I want to replace the 500GB Momentus XT that's in my 17" MBP now. I've got the drives and the hardware to replace the optical drive is on its way.

    My main question - just to see if anyone has some recommendations here - is which bay to put the SSD in... the regular hard drive bay under the palm rest? or in the optical bay?

    I'm assuming there will be no speed difference. Is that correct?
    Any thoughts on noise/vibration coming from the HDD and which bay would be best for that?
    Any other considerations?

    Also, I've searched and couldn't find anything yet... do anyone know if there's a way to see the contents of each drive when they are fused? Not wanting to manage, just observe.
  2. Middleman-77 macrumors member

    Nov 29, 2012
    Hi there,

    I've had some experience with creating my own Fusion drive so I could probably help. You can follow this guide for your setup, as this guy is using the same 17" MBP. >

    a) I would suggest stick only using either OCZ Vertex/Agility 3/4 or Samsung SSDs, and Hitachi/WD HDs at the moment because there is a high chance of incompatibility when creating the Fusion Drive. I have experienced this with my setups and got numerous errors mainly unable to create a Logical Volume (Fusion Drive) with Intel 520 or a Kingston V+200 SSD.

    b) Secondly there are certain models of Macs which are reported to have experienced problems with Fusion Drive. The early 2011 15" MBP is one of them. >

    c) You are right to remove the Seagate Momentus XT as the Fusion Drive only works with ONE SSD and ONE HD (the process of creating the Fusion Drive is partly encryption by the OS). The person posted in the above forum post was probably experiencing problems with his 15" MBP because he used the Momentus XT as a replacement (which as you know contains a small SSD).

    But once it is up and running, it is incredibly fast. I tried cloning from an 250 SSD to the Fusion Drive with a SATA3 240GB SSD & 2TB HD and it just took like less than 7 minutes to copy over 8GB worth of data!

    About how it works, this is from what I have read and observed. Well what the Fusion drive does is basically cache the most used files in your system on the SSD, storing the rest in the HD so that it frees up your time, resulting in super speedy reads and writes. When you are copying files over for instance from one drive to the next, the data is copied first over to the SSD (because it is the quickest), then gradually transferred over to the HD in the background while idle. This is why it is worth considering over a traditional HD setup.

    And to answer your question about the data there is NO WAY for you to see the contents of each drive, because it is all done in the software. Both drives contents will be seen 'as one logical volume' under the OS and there is no way to 'see it'.

    As such I advise once you've created the Fusion drive, to backup your Fusion volume with a single external drive frequently using drive cloning software like Carbon Copy Cloner or Superduper especially if it is your main drive and to use Time Machine if needed, because we currently do not know what is the reliability of such a setup. Its still early stages at the moment for many and its better to take precautions with such a setup. :)
  3. SuperRob macrumors 6502

    Mar 14, 2011
    Put the SSD where the hard drive normally is, and your HDD in the Optical bay. Some MBP's have had issues getting full speeds from the optical bay with an SSD, so it's safer to have your spinning drive there.

    Contrary to what Middleman-77 said, I would avoid some OCZ SSDs. There have been lots of incompatibility reports there. Samsung drives, being what Apple uses, are likely safest. That said, I have a Crucial M4 in my mini in a Fusion config, and it was flawless.

    Also to correct this perception that the SSD is somehow "caching" what is on the hard drive, Middleman-77's description is incorrect. The SSD is your PRIMARY storage device. The HDD is used for storage overflow. If you don't have enough data to completely fill your SSD, all of it will live on the SSD, and the hard drive will sit idle. Once the SSD fills up, it will start moving lesser used data down to the HDD. If you start reading files from the HDD regularly, OS X will promote that data up to the SSD, and demote some lesser used data back down to the HDD. These files are MOVED, and you will not have data living on both drives. All of this will be seamless to you, however.
  4. 3282868 macrumors 603

    Jan 8, 2009
    Any benefit to this on a current gen Mac Pro with a SSD in one optical bay and one of the HDD in the four bays? Assuming this is mostly beneficial to systems with 1 SSD and 1 HDD, might be pointless with 5 internal drives?
  5. Heb1228 thread starter macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    I've got it up and running and am pretty happy with it so far. Definitely a good performance jump in a lot of things. I had already ordered the drives, and went with a Sandisk Extreme for the SSD. I did put that in the regular hard drive bay and I think that was the best choice as far as noise & vibration.

    This is on a Mid 2009 17" MBP in case anyone else has this model and is wondering since someone mentioned incompatibility with certain models.
  6. Heb1228 thread starter macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    Just an update, two weeks in and I've been really happy with how it's worked. I don't think I've seen a beachball since I installed the thing. Performance is excellent. This laptop only has a SATA II controller, so I think the performance could be even better on a newer model.

    My only complaint is that sometimes the HDD is a little noisy. Vibrations are occasionally noticeable and I think it's because the OWC mounting bracket only had two screws holding the hard drive in. It might could benefit from some kind of vibration dampening device or different/additional way to secure the drive. But its a pretty minor thing, have only noticed it a few times in two weeks. Might open it back up and see if I can figure out a homemade way to quiet it down a little.
  7. LeandrodaFL macrumors 6502a


    Apr 6, 2011
    Can I fusion drive with 480GB SSD? Macmini 2012

    I'm researching the MacMini 2012 Quad-core capabilities. Can I put in the 2nd bay a 480GB and Fusion drive with the 1TB HDD? Or is the limit 120GB as Apple advertized? What about 240GB?
  8. nsfw macrumors regular

    Aug 21, 2009
    Since I have the attention of people who have experience let me hijack this thread a bit.
    How do you guys think fusion is going to handle really large files?
    I work with vmware fusion which for me has 50GB+ bundles with 2GB vmdk vmware disk files. So basically the OS is chopped up into a bunch of smaller 2GB file.
    I know little about fusion, but having to swap in and out large 2GB files seems like a bit of overkill for fusion? I'm going to give it a try, but I don't have high hopes.
  9. gnasher729 macrumors P6


    Nov 25, 2005
    Fusion operates on blocks of 128 KByte. If one of these 2 GB VMWare files contains 500 Windows files that are used a lot, and 1000 Windows files that are rarely used, the ones that are used a lot will move to SSD, and the others won't.

    There shouldn't be any limit. However, since Fusion with 120 GB SSD is "almost as fast as SSD", Fusion with 480 GB SSD will not be much faster, but of course much more expensive.
  10. donlab macrumors 6502


    Jun 3, 2004
    CoreStorage executes moves at block level not file level. It will be fine.

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