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  • Disk Mark Questions

    Hi all, I have some questions on interpreting some disk mark results. Key parts of the testbed are:
    • Dell R720DX server
    • 128GB Ram, 2x E5-2690 CPU
    • LSI 9207-8i SAS/SATA Card - Flashed to the latest IR firmware
    • 2x Samsung 860 EVO 1TB SSD Drives
    • Windows 2016 Standard - Not virtualized, installed on the SSDs
    My goal is to determine the performance penalty for mirroring the SSD drives, using hardware mirroring with the LSI Card.

    ============

    I've included pictures below, but to summarize:

    In unmirrored mode:
    • Disk Mark = 4627
    • Disk Seq Read = 453
    • Disk Seq Write = 403
    • Disk Random Seek + RW = 422
    In mirrored mode:
    • Disk Mark = 2565
    • Disk Seq Read = 455
    • Disk Seq Write = 203
    • Disk Random Seek + RW = 50

    ======

    Observations:
    • Disk Mark in unmirrored mode matches other reports from other systems. It tells me this system is performing normally in this mode.
    • Sequential read performance is unaffected by the mirroring. That makes sense.
    Questions
    • Sequential write speed is 50% when mirroring. Is that expected when using hardware mirroring? I would have thought the card could drive more writes in parallel to the 2 drives. Am I missing a tuning parameter somewhere?
    • What is the Disk Random Seek + RW telling me? Going from 422 to 50 doesn't make sense
    Unmirrored Mirrored

  • #2
    If speed is really an issue you might be better off with a newer M2 SSD setup. You would get at least 4x the performance.

    I would have also thought the RAID controller would to parallel writes. With the result being the slowest of the two drives. I am not really familiar enough with the LSI 9207-8i to offer any tuning advice. Did you look at the caching policy (Writeback vs WriteThrough)

    Try Microsoft's dynamic disks (software RAID) with direct SATA connections to the motherboard. You might get a better result.

    There is also the Advanced disk test in PerformanceTest if you want to experiment with different scenarios.

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