Slow "Read" speeds on 2 new HDDs

Discussion in 'Mac Pro' started by CalfCanuck, Oct 18, 2012.

  1. CalfCanuck, Oct 18, 2012
    Last edited: Oct 18, 2012

    CalfCanuck macrumors 6502a

    Joined:
    Nov 17, 2003
    #1
    I just finished installing 2 new WD drives in my 2008 MP (bays 3 & 4). I ran the diglloyd DiskTester fill-volume test to condition them, and got some strange results - the "Read" results on both drives lagged write by a huge margin.

    Here's the 2 graphs, along with a sample from the Excel template (that matches early HDD tests from a few years ago).

    I turned off Spotlight and Time machine before the tests, and actually re-ran the 3TB drive test twice with everything running in my Dock turned off. Any ideas what is going on?

    1. WD Caviar Black, 2TB:
    http://www.weitergehts.com/images/WD_Caviar_Black_2TB.png

    2. WD Caviar Green, 3TB (for Time Machine).
    ]http://www.weitergehts.com/images/WD_Caviar_Green_3TB.png

    3. Sample graph, from excel template:
    http://www.weitergehts.com/images/Sample_graph.png

    (Edit: 10.6.8, 18GB)
     
  2. Spacedust macrumors 6502a

    Joined:
    May 24, 2009
    Location:
    Poland
    #2
    Seems to be ok. Mac Pro's doesn't have SATA/600 controller.
     
  3. CalfCanuck thread starter macrumors 6502a

    Joined:
    Nov 17, 2003
    #3
    Interesting. So if I had used a SATA II drive instead, I would have gotten better performance? I had assumed backwards compatibility, but not a speed hit...
     
  4. theSeb macrumors 604

    theSeb

    Joined:
    Aug 10, 2010
    Location:
    Poole, England
    #4
    NO. There is no speed hit and SATA II is more than fast enough for a single HDD. I don't know exactly what type of files that test is using (small, large etc), but the results don't look like there is anything wrong. Everything looks perfectly fine.

    ----------

    So what? A single HDD cannot saturate SATA II, so having SATA III will make no difference.
     
  5. derbothaus macrumors 601

    derbothaus

    Joined:
    Jul 17, 2010
    #5
    You'd get the same performance on SATA1 actually. You need more than one HDD RAID'd to saturate SATA bus. (Some very fast exceptions) Like 1TB Raptor. SSD's are a whole other ballgame.
     

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