Dual SSD w/ Fusion?

Discussion in 'Mac mini' started by Chabba, Dec 9, 2013.

  1. Chabba macrumors regular

    Jul 17, 2011
    Anyone run dual SSDs in Fusion?
    I recently came into a mid-2011 Mac Mini. I ordered a 256GB SSD and can get a 128GB for a great price. The 256GB should be fine, but the 128GB would be a good buffer just in case.

    The person who will ultimately have the computer does not have much knowledge about Macs in general. By not much, I mean 0 experience. I'd like the two drives show as 1 volume, so the user doesn't have to worry about it at all.

    So, has anyone run dual SSDs in Fusion? I don't want a regular spinning drive if I can help it.
  2. ricosuave macrumors 6502


    Mar 27, 2007
    In front of my mac
    With two SSDs, two sizes, you might as well build a JBOD. This way you get the speed, combined size, and one volume. With Fusion, you may run risks because it's not officially supported and no added benefit over JBOD.
  3. dan1eln1el5en macrumors 6502


    Jan 3, 2012
    Copenhagen, Denmark
    I have one of those minis.

    I have a regular SSD and a HDD, the generation of minis doesn't support fusion drive natively, so you need to do some terminal tweaking. but it should be doable.
    (My set up is regular system, applications etc. is on SSD, home drive and work drive on the HHD, works...not as fusion, but it's fine)
  4. Chabba thread starter macrumors regular

    Jul 17, 2011
    That's what I'll do. JBOD, 2 disks, 1 volume.

    Thank you!
  5. blanka macrumors 68000

    Jul 30, 2012
    You can also try Raid 0. Then you benefit of 2 SATA channels, and you might be able to get PCI speeds.
    Fusion on SSD's is complete BS.
  6. haravikk macrumors 65816

    May 1, 2005
    Got some evidence for that?

    Fusion Drive with SSDs is definitely possible, the question is whether you will see any advantage, and to answer that depends on the SSDs being used; some higher volume SSDs may be slightly slower than others, in which case a faster SSD with a slower, larger SSD could still yield some benefit. But then by the same token, many smaller SSDs actually use fewer memory chips, which means they're slower overall than otherwise identical drives with larger capacities.

    You'd really need to get benchmarks for both drives and decide if a) one of the SSDs is faster and b) if it's fast enough to warrant doing this.

    Strictly speaking there's no harm in doing a Fusion Drive as opposed to a JBOD/concatenated set, as both will most likely be ruined if one of the drives in the sets fails. However, JBOD's performance will be at the mercy of the drive that data ends up on, while the Fusion Drive will keep more common files on the speedier of the two, provided you setup it up correctly.

    That all said, you're still only going to see the speed of a single SSD; RAID-0 and RAID-1 both offer theoretically better performance overall because you can read from both disks simultaneously, but really you should have identical disks to run either of those.

    The last alternative is of course self-managed, which doesn't necessarily have to be difficult. For example, you can install the OS onto the fastest of the two SSDs, then move the user folder(s) onto the other SSD, as this will mean that the OS can working with one drive while the user simultaneously works with the other, which effectively gives you better multi-tasking performance. While a single volume can be easier, a separate OS and users volume isn't that hard to handle IMO, though you may waste some excess capacity on one or both drives.

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