Multi threaded RAID 5

  • Hello all,


    I'm running 2.2.5 on a dual core Atom machine and I am just building a RAID 5 array with software raid. Well, the speeds are not amazing. I thought to speed up the array by making the hash calculation multithreaded which should be possible by

    Code
    echo 2 > /sys/block/md127/md/group_thread_cnt

    since Kernel 3.12. But there is no entry group_thread_cnt in the sysfs. Is our kernel build without this or is there a way to enable?


    Thanks

    • Offizieller Beitrag

    If you are on OMV 2.x, you are using the 3.2 kernel which wouldn't have this (too old). You need to install the backports 3.16 kernel. There is a button to do this in the omv-extras plugin.

    omv 7.0.4-2 sandworm | 64 bit | 6.5 proxmox kernel

    plugins :: omvextrasorg 7.0 | kvm 7.0.10 | compose 7.1.2 | k8s 7.0-6 | cputemp 7.0 | mergerfs 7.0.3


    omv-extras.org plugins source code and issue tracker - github


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    • Offizieller Beitrag

    I can confirm it is in the 3.16 kernel and the sysfs entry exists.

    omv 7.0.4-2 sandworm | 64 bit | 6.5 proxmox kernel

    plugins :: omvextrasorg 7.0 | kvm 7.0.10 | compose 7.1.2 | k8s 7.0-6 | cputemp 7.0 | mergerfs 7.0.3


    omv-extras.org plugins source code and issue tracker - github


    Please try ctrl-shift-R and read this before posting a question.

    Please put your OMV system details in your signature.
    Please don't PM for support... Too many PMs!

    • Offizieller Beitrag

    Did you test the setup with the 3.16 with the group thread count set to 0? I'm just wondering how much speed increase came from the newer kernel and how much came from the multi-threading.

    omv 7.0.4-2 sandworm | 64 bit | 6.5 proxmox kernel

    plugins :: omvextrasorg 7.0 | kvm 7.0.10 | compose 7.1.2 | k8s 7.0-6 | cputemp 7.0 | mergerfs 7.0.3


    omv-extras.org plugins source code and issue tracker - github


    Please try ctrl-shift-R and read this before posting a question.

    Please put your OMV system details in your signature.
    Please don't PM for support... Too many PMs!

  • The speed came from the newer kernel, because CPU usage now is about 25% before about 60%. I think the bottleneck now is the PCI SATA controller. Setting thread count to 2 or higher actually decreases performance.

    • Offizieller Beitrag

    Thanks for the update.

    omv 7.0.4-2 sandworm | 64 bit | 6.5 proxmox kernel

    plugins :: omvextrasorg 7.0 | kvm 7.0.10 | compose 7.1.2 | k8s 7.0-6 | cputemp 7.0 | mergerfs 7.0.3


    omv-extras.org plugins source code and issue tracker - github


    Please try ctrl-shift-R and read this before posting a question.

    Please put your OMV system details in your signature.
    Please don't PM for support... Too many PMs!

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