RAID 0 (4 x SSD) MAX Speed?

Discussion in 'Mac Pro' started by scottrichardson, Nov 10, 2012.

  1. macrumors 6502

    Joined:
    Jul 10, 2007
    Location:
    Ulladulla, NSW Australia
    #1
    Hi all,

    If I install FOUR SSDs in my Mac Pro and configure them in RAID, what's the theoretical max throughput I could expect?

    I understand the 300MB/sec limit of SATA-II - so does that mean 4 disks will each theoretically have 300MB/sec, with a combined theoretical total of 1200MB/sec?

    I'm considering installing an OWC Accelsior 240GB PCI SSD Card as my boot drive, then running 4 x 120GB SATA-II SSD's as my main projects/work volume raided together.

    Anyone else done a 4-way SSD RAID 0 internally here?

    ----------

    It appears I should have searched first, looks like 650MB/sec is the max speed I can get.

    http://forums.macrumors.com/showthread.php?t=1400474

    I already have 2 x Vertex 2 120GB in a RAID 0 stripe, and I only get about 300MB/sec from that. So I assume 4 drives will get close to saturation?

    ----------

    Considering the above, it may be better to simply buy two OWC Eccelsior PCI SSD cards.

    One for OS/Apps, and another, 480GB one for data storage/files.

    800MB/sec on both.

    PS I do everything from Video Editing, Audio Engineering, Web Development, Graphic Design etc.

    Specs of my machine in my sig.
     
  2. macrumors 6502

    JavaTheHut

    Joined:
    Aug 15, 2010
    #2
    I have been thinking about this also ie. 4 ssd in raid. What I concluded was to go the way of a backplane and a Areca Raid Bootable card and get the power from the spare sata cable in the ODD bay2 with the use of a cable split.

    This would bring in the sata III speed I believe?
     
  3. macrumors demi-god

    Gav2k

    Joined:
    Jul 24, 2009
    #3
    You will saturate the bus fully. Your best bet is to find out how many it has. I know from pc use some early boards had 1 bus over 2-4 ports later boards had multiple.
     
  4. Loa
    macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #4
    Hello,

    4 SSDs in the bays will pretty much saturate the bandwidth.

    As for the 2 Accelsior, you may have to put one of them in the lower slots, because the top 2 slots share the same bandwidth.

    Loa
     
  5. macrumors G4

    Joined:
    May 6, 2008
    #5
    If they're being used on the MP's SATA ports, the SATA controller tops out at ~660MB/s.

    To get past this, you'll have to use a suitable PCIe card (8x lane card for a single model so the data isn't throttled, so not cheap <most of these are actually RAID cards>).

    BTW, using RAID 0 is more dangerous to your data than a single disk. This is still the case with an SSD stripe set vs. a single SSD.
     
  6. thread starter macrumors 6502

    Joined:
    Jul 10, 2007
    Location:
    Ulladulla, NSW Australia
    #6
    I think 660MB a sec is fine for what I need - and I have no issues with the 400% increase in failure potential as it will all be backed up via Time Machine and also regular cloned copies.

    At this stage it's either 4 x 120GB SSDs in a 480GB RAID 0 stripe for ~660MB/sec.....

    or..

    1 x 480GB PCIe OWC Accelsior for about the same speed.

    Price difference is $480 vs $750.

    ----------

    Hmm. OK so I have 4 slots total, obviously. GPU in bottom slot. Boot Accelsior in 2nd slot. Files Accelsior in 3rd slot, and my USB3 card in the top slot?
     
  7. macrumors 6502a

    Joined:
    May 24, 2009
    Location:
    Poland
    #7
    I've acheived almost 900 MB/s with Areca ARC-1231ML and a Mac Pro 2009 :D

    [​IMG]

    It was about 150 MB/s less on a Mac Pro 2008.
     
  8. Loa
    macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #8
    Nano would be able to answer this question a lot better than I would. :)

    My first guess: put the boot in the slower (3 or 4) slot: work needs more speed than boot.

    Loa
     
  9. thread starter macrumors 6502

    Joined:
    Jul 10, 2007
    Location:
    Ulladulla, NSW Australia
    #9
    Seems that card is no longer available? Also how did you attach the SSD's? You need to clearly bypass the internal SATA connectors right?
     
  10. macrumors 6502a

    Joined:
    May 24, 2009
    Location:
    Poland
    #10
    It's available on german eBay in a very good price :)

    I've used 1m miniSAS -> 4xSATA cable directly via small hole in optical drive bay into a 6x2,5" backplane instead of second optical drive. Works great and all standard drives will fit too, but you have to put the cable on top of the side of front fan ;)
     

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