# [OmniOS-discuss] FW: Fibre Channel performance on OmniOS

Kyle Bruene KBruene at simmonsperrine.com
Wed Aug 20 14:25:57 UTC 2014

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    I'm ok with losing data from power loss or panic. I have two of these boxes that are normally run in a mirror configuration at the host level. These are being used VM's. It is indeed a single data steam. The test is being run over a single LUN. Does multipathing not split the stream between two paths?

    Hyper-V connects to these boxes and mirrors them. Maybe it just depends on if the Hypervisor will access the VHD file in multiple streams or just a single one.

    -----Original Message-----
    From: Bob Friesenhahn [mailto:bfriesen at simple.dallas.tx.us]
    Sent: Wednesday, August 20, 2014 8:54 AM
    To: Kyle Bruene
    Cc: omnios-discuss at lists.omniti.com
    Subject: Re: [OmniOS-discuss] FW: Fibre Channel performance on OmniOS

    On Wed, 20 Aug 2014, Kyle Bruene wrote:

    >
    > I’ve tried different pool configurations. Currently I have two pools:
    > the 5 ssd’s in a raidz and the 3TB’s in a raidz. I get the same result
    > from both because the cache is so large. With sync off, I get the same
    > speed on both pools because it is just writing/reading to/from ram. I
    > feel like there is enough hardware and was hoping to get better speed
    > than this with more SSD’s. I am assuming that if I setup some kind of ramdisk, I would still only get the 400MB/s over FC. Reading and writing to the pool(s) locally produces multiple GB/s.

    What method are you using to measure throughput?  It may be that your setup will increase throughput with more independent data streams but perhaps your benchmark methodology might only be using one data stream.

    If there is a fixed response latency somewhere (e.g. SSD sync write
    time) then single-app throughput would not likely increase as more parallelism is added to the hardware and topology.

    Even with zfs zil disabled, the disks/SSDs need to accept writes and cache flushes for each transaction group.  Without these cache flushes, your pool would likely be toast on the first power loss or system panic.

    Bob
    --
    Bob Friesenhahn
    bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
    GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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