Pegasus2 Performance

Discussion in 'Mac Accessories' started by jasonvp, Apr 12, 2014.

  1. jasonvp macrumors 6502a

    jasonvp

    Joined:
    Jun 29, 2007
    Location:
    Northern VA
    #1
    Originally posted in another thread in the Peripherals section:

    I've been seeing what I'd call "interesting" performance issues with the Pegasus2 enclosures that I have connected to the new Mac Pro. Each is on its own Thunderbolt channel. One has 4 drives in it, with 2 RAID0 volumes. The other has 2 drives in it, also in a RAID0 volume. These RAID volumes were created using the Promise utility, not OS X.

    The drives in question are 7200RPM SATA2 or SATA3; they're certainly not the fastest things available.

    What I've found with Blackmagic is inconsistent read and write results. Sometimes a volume will get 200+MB/s reads and writes. Other times it'll stumble with the test first starts, and stay around 10MB/s (not a miss-print). It applies to both enclosures.

    As a test, I nuked two of the volumes, reset the drives to "Pass-Thru" mode, and recreated the RAID0 volumes in OS X software. The results? Consistent performance numbers of ~250MB/s on reads and writes. Not necessarily better, but reliable.

    At this point, I can't recommend the Pegasus2's internal RAID controller if performance is needed. Certainly if you intend on using RAID5, which OS X doesn't support internally, then the enclosure's controller would work. But if you're just doing RAID0 or 1, there's really no reason to not use software RAID. The CPU in the Mac is certainly significantly more powerful than what's in the enclosure, and handling RAID/storage requests won't make it break a sweat at all.

    What have others found?
     
  2. snouter macrumors 6502a

    Joined:
    May 26, 2009
    #2
    Out of the box RAID 5 with the Toshiba drives I'm seeing 450-600MB/s write and 400MB/s reads.
     
  3. RoastingPig macrumors 68000

    RoastingPig

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    #3
    try some real world test by copying lets say like a 50gb folder and time it on a pegasus raid0 configuration and then the same but with the osx software raid...to see if theirs any difference
     
  4. VirtualRain macrumors 603

    VirtualRain

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    Vancouver, BC
    #4
    +1. BlackMagic is not that reliable.
     
  5. jasonvp thread starter macrumors 6502a

    jasonvp

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    #5
    The problem with doing that is the disk cache intrinsic with OS X. While real world tests are useful in some cases, synthetic benchmarks are a better way to do direct comparisons of the disks like this.

    Based on what? It's used in every benchmark I've come across.
     
  6. RoastingPig macrumors 68000

    RoastingPig

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  7. jasonvp thread starter macrumors 6502a

    jasonvp

    Joined:
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    Northern VA
    #7
    AJA results for the same pair of disks using a 4GB file size:
    Software RAID writes: 220MB/s
    Software RAID reads: 230MB/s

    Hardware RAID writes: 290MB/s
    Hardware RAID reads: 180MB/s

    The results are interesting, and given the faster reads, I think I'll stick with the software RAID0.
     
  8. VirtualRain macrumors 603

    VirtualRain

    Joined:
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    #8
    Based on a number of experiences just like yours. It seems to be unreliable with some externals in particular.

    Consider buying Quickbench if you're looking for a serious benchmarking tool.
     
  9. RoastingPig macrumors 68000

    RoastingPig

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    #9
    quick bench is the anandtech recommendation for benching..it cost $15 buck tho
     
  10. VirtualRain macrumors 603

    VirtualRain

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    #10
    Which is much less than the value of everyone's time spent in this thread because of a free tool that works when it wants to. ;)
     
  11. jasonvp thread starter macrumors 6502a

    jasonvp

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    #11
    Back it up and I'll be happy to believe you. Otherwise you're contributing precisely nothing to this thread, and you're completely free to: move along.
     
  12. VirtualRain macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #12
    Sheesh, why so harsh? I'm trying to help you get consistent benchmarks rather than waste your time troubleshooting a problem with the Pegasus2 that may not exist.

    May I present to you, your own experience as evidence?

    Which happens to mirror my own experience... it was very unreliable on my own external WD Duo setup whereas QuickBench and timing file transfer tests worked fine.

    At any rate, I'm moving along now. Seeya.
     

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