Who's running SSD's in RAID0

Discussion in 'Mac Pro' started by VirtualRain, May 24, 2009.

  1. VirtualRain macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #1
    Hi, who here is running two or more SSD's in RAID0?

    What did you use for a stripe size? Why (theory, test results, source)?

    Thx! :)
     
  2. aaronw1986 macrumors 68030

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    Oct 31, 2006
  3. richard.mac macrumors 603

    richard.mac

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    #3
    this guy does. though its a Samsung viral video and not commercially viable yet.
     
  4. cosmos macrumors regular

    cosmos

    Joined:
    Dec 17, 2003
    Location:
    Cincinnati, Ohio
    #4
    Something to consider

    I googled SSD performance and found that while they have great initial speeds, their performance degrades over time.

    I suggest that anyone looking into SSDs consider this if they are looking for the absolute performance in their systems.

    http://perspectives.mvdirona.com/2008/04/25/LaptopSSDPerformanceDegradationProblems.aspx

    From what I gather, higher cost SSDs should perform better over time vs. entry level lower cost units.
     
  5. VirtualRain thread starter macrumors 603

    VirtualRain

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    Aug 1, 2008
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    Vancouver, BC
    #5
  6. whatisthe macrumors member

    Joined:
    Apr 10, 2008
    Location:
    CT
    #6
    I'm running two x25-m's in raid0. I decided on a 64k stripe size as some of the sites i visited while researching seemed to recommend it. I didn't have the patience to take time finding the optimal stripe size for these ssd's but I'd be very interested to see the optimal stripe sizes for different uses of the raid (os/app drive, photo scratch disk, video scratch disk, etc.)

    I posted some speed results here: http://forums.macrumors.com/showthread.php?t=698503
     
  7. VirtualRain thread starter macrumors 603

    VirtualRain

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    Aug 1, 2008
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    Vancouver, BC
    #7
    I polled the experts over on another IT related forum... here are some of their insights...

     
  8. VirtualRain thread starter macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #9
    I'm reposting this from another thread because it's very relevant here...

    I think I get it...

    I found this additional explanation...

    Basically, the smaller the write erase block, the better.

    Also, I see now why you want your stripe size to match or exceed your write erase block size... If the SSD has to write erase 128K of data regardless of the data being committed to disk, you might as well have a matching stripe.

    Example (if I understand this correctly)

    If the OS is writing 128K to disk and you have a stripe size of 32K and a write erase block size of 128K, then that write will be split into four stripes across both drives which have to each write erase two 128K blocks... thus a total of 512K has to be rewritten. Very ineffecient.

    In conclusion:

    Since Intel X25-M drives reportedly have 128K write erase blocks, it's prudent to use a 128K stripe size when RAIDing these drives.

    That's what I've chosen.
     
  9. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #10
    Nice bit of research. :)
     
  10. pprior macrumors 65816

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    Aug 1, 2007
    #11
    I was wondering about this as well. given the 160gb Intel SSD is about twice the price of the 80, why not just buy 2 x 80 and RAID-0 them. Same size, twice the speed.
     
  11. nuckinfutz macrumors 603

    nuckinfutz

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    Jul 3, 2002
    Location:
    Middle Earth
    #12
    A lot of us are thinking along the same lines. If I'm not saving an appreciable amount on say going without double the size I may as well see if I have the open bays to leverage multiple drives.

    I'd love to see an Intel RAID-10 setup with four 80GB drives.
     
  12. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #13
    How many would be willing to part with $1256 + S/H to try it though? ;) :p
     

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