[SLOW?] 2013 iMac, 240 GB Corsair Force GS, Seagate thunderbolt

Discussion in 'iMac' started by mdb90, Jun 29, 2013.

  1. mdb90, Jun 29, 2013
    Last edited: Jun 29, 2013

    mdb90 macrumors newbie

    Joined:
    Dec 27, 2012
    #1
    Hi all,

    I am booting my new 27" 2013 iMac from a 240GB Corsair Forcs GS (SSD) drive, using a Seagate Thunderbolt adapter. When performing a (blackmagic) write/read test, results stuck at 200 / 300 MB/s. That's much faster than a traditional drive, but to be honest, I was expecting a bit more performance.

    Attached the speed test, and a screenshot from system information. (in Dutch, but you'll get it, I think ;) )

    Is there anything I can do to improve the write/read speeds?
     

    Attached Files:

  2. Chippy99 macrumors 6502a

    Joined:
    Apr 28, 2012
    #2
    To be fair that is a bit slower than I would have thought (sorry I can't tell you why though).

    I don't use it these day but from memory when I had a Sandisk Extreme 256GB SSD attached to the Seagate Thunderbolt connector, I used to get around 300MB/s data transfer speeds. Can't remember exactly but I am sure it was around that number.

    And to be honest 130/170 is not that much faster if at all than a traditional drive. My LaCie Blade Runner 4TB via USB3 was getting around 180/180.
     
  3. mdb90 thread starter macrumors newbie

    Joined:
    Dec 27, 2012
    #3
    It turned out that Trim was disabled. Had it enabled when I installed OS X on it though.(using Trim enabler) Now speeds are up to 200MB/s write and 300 MB/s read. That looks already a bit better.

    Compared to my retina MBP there is still a difference (325MB write, 435MB read). Any possibilities to narrow that gab?
     
  4. Chippy99 macrumors 6502a

    Joined:
    Apr 28, 2012
    #4
    Do you mean you get 325/435 from the Corsair SSD and Goflex adapter connected to the MBP? That would surprise me as I didn't think the adapter would go that fast. I think that's the limiting thing in the equation, it's only SATA II and it's not that quick in the great scheme of things.
     
  5. WilliamG macrumors G3

    Joined:
    Mar 29, 2008
    Location:
    Seattle
    #5
    Get a different SSD? My Samsung 830 256GB gives me ~360MB/325MB read/write.
     
  6. hfg macrumors 68040

    hfg

    Joined:
    Dec 1, 2006
    Location:
    Cedar Rapids, IA. USA
    #6
    As discussed in many threads here, SSDs with Sandforce controllers will have slow test results using BlackMagic DiskSpeedTest due to the data stream used for testing (non-compressable data). Using a different test program (AJA) will display better results due to the test algorithms used.

    The SSD is probably just fine and will perform well as a OS X boot disk despite what the test program seems to indicate.
     
  7. WilliamG macrumors G3

    Joined:
    Mar 29, 2008
    Location:
    Seattle
    #7
    Ah yes I'd forgotten about that. That drive is rated faster than the Samsung 830, so I've no doubt it's probably pegging the enclosure at similar speeds to my Samsung 830 (since that enclosure doesn't tend to allow more than roughly 385MB/s read and about 340MB/s writes, even with an 840 Pro).
     

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