Dual ssd fusion drive?

Discussion in 'Mac Pro' started by push/pull, Nov 1, 2013.

  1. push/pull macrumors newbie

    Oct 31, 2013
    Has anyone tried a dual ssd fusion drive? I have two 128 gb crucial drives, a M4 and V4. I'd like to create a fusion drive in Mavericks with the M4 as the "lead"(?) drive. Any advice ? Is it worth it?
  2. Small White Car macrumors G4

    Small White Car

    Aug 29, 2006
    Washington DC
    I see the logic behind this idea but I strongly suspect that it's not worth it.

    The fact is, a fusion drive puts a strain on your system by constantly requiring it to move stuff around. It's worth it only because hard drives are so slow that the difference between the SSD and the HD is large enough to make the 'pros' outweigh the 'cons.'

    I suspect that the difference between your 'faster' and 'slower' SSD is not nearly great enough to be worth exploiting. In other words, you'd lose more than you gain.

    I have no math here to back me up, but this is my gut reaction. If someone can prove me wrong, please do.
  3. deconstruct60 macrumors 604

    Mar 10, 2009
    I highly doubt CoreStorage is going to make note of any relatively small difference between the drives. It is a safe assumption to built into CoreStorage's heuristics that a SSD has significantly faster access times than a HDD. They are a "pair" of different devices with different strengths.

    Two SSDs there are no significant differences. Even SATA 300 vs SATA 600 isn't a gap like a that of a rotational latency versus no rotational latency. The capacity is exactly the same (how much infrequently accessed material actually going to offload? ) In fact, putting all of the write load on one SSD rather two can hardly be a 'good' thing over the long term. If just had a 256GB SSD drive wouldn't have to write the data 2-3 times to 'spill' it back and forth between the drives. That is less wear and just as good if not better performance for not radically different money.

    If had a RAM based SSD and a Flash SDD then there would be a big gap in capacity vs. speed between the two.
  4. push/pull thread starter macrumors newbie

    Oct 31, 2013
    Ok so it would be better to do my own data management or sell the V4 and get a larger capacity HDD.

    Right especially in my Sata 300 Mac Pro!

    This is effectively what I wanted to create with the fusion set up. I already have these drives, so a new 256 ssd is off the table.

    The V4 is not a particularly good ssd. If I do the same things over and over it is ok. When I do something out of the ordinary (large writes or changes in settings) it gets noticeable slower. I was hoping to eliminate it's data management problems.

    I'd hate to lose the performance of the M4, it is noticeably better(or at least consistent). I will probably use the V4 as a data drive and point my software to use that for libraries and storage.

    Thanks for the help!
  5. ssls6 macrumors 6502a


    Feb 7, 2013
    Both in Raid 0 is a way better proposition. Same size, 256, 2x the access speed.
  6. push/pull thread starter macrumors newbie

    Oct 31, 2013
    Sweet! Don't you needed special equipment to do Raid? I will research this option for my Mac Pro.


    I looked up Raid 0 and it can be done with out hard ware:)

    Would there be an issue with one drive being Sata 300 and the other is Sata 600?

    there is probably a thread on that already. I'll look for it.
  7. ssls6 macrumors 6502a


    Feb 7, 2013
    You are good. Just use Disk Utility to create a raid 0 from the two and let it rip. If it is your installation drive, you won't have a RP. If you want a recovery partition, it needs to be created before the Raid volume is created and then you may need to create it manually. I'm not sure. As long as you have an install USB or a recovery USB, you don't really need a RP on the boot drive.
  8. haravikk, Nov 1, 2013
    Last edited: Nov 1, 2013

    haravikk macrumors 65816

    May 1, 2005
    I have a V4 SSD I use as a portable drive so I can understand the dilemma; it's random access performance (especially read + write together) is horrible, still much better than a USB thumb stick, but nothing like better SSDs. But is there no way you could just get a cheap(-ish) HDD to use instead?

    As for whether it works; I'm not sure Fusion Drive does any kind of profiling of drives, I think it's currently a bit more primitive than that. i.e - if you create a core storage volume and the first drive added is an SSD, then you get a Fusion Drive, otherwise you don't.

    So it should work as long as you add the M4 first, and in the particular case of an M4 feeding into a V4, it could work pretty well actually. I'm not sure you're likely to find many people who've tried it though, so it's probably a case of just trying it yourself and seeing how it turns out; make sure you put enough data on the volume to exceed the M4's capacity, and see how the performance measures up and go from there.

    I wouldn't recommend an SSD RAID at all for an M4 + V4; while you will nearly double the speed for stuff the V4 is fine at (continuous single read/write), anything that the V4 struggles with will cripple the M4's performance. The only RAID option really would be concatenating the drives, but while you might lessen the V4's performance issues by spreading your data out, you can't guarantee where your data will end up; applying a system update could end up putting system files on the V4 for example. If you absolutely need to combine these drives into one volume then your Fusion Drive idea is definitely the best one to try.
  9. push/pull thread starter macrumors newbie

    Oct 31, 2013
    I just did a bunch of web scouring. I could have just waited for haravikk's response. That is exactly the conclusion I came to.

    Ever since I bought the V4 I do a lot of research before I pull the trigger. I'd rather go in knowing i may be disappointed rather than surprised by poor performance.

    It seems the best performance option may be to manage my data between the 2.

    However I like the idea of not worrying about that (read lazy);)

    I will probably try the fusion set up any way since the funds for this machine are nill and a hdd is not an option right now.

    I will definitely post how it goes if/when I do.

    Thanks for all your expertise on this.

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