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    Subjectio-scheduler tuning for better read/write ratio

    I'm trying to tune the kernel/io-scheduler for better read/write
    ratio on a Areca RAID0 device (4 disks, kernel 2.6.26, xfs fs).

    I can get 200 MB/s seq. writes and about the same for seq. reads. My
    problem is that if there are reads _and_ writes on this device, the
    write throughput is much higher than the read throughput (40 MB/s
    read, 90 MB/s write).

    The deadline scheduler sounded like the way to go for getting better
    read results, but reagardless which parameter I change, the ratio keeps
    the same.

    cfq, noop.. different paramter settings, but alway the same result.

    short: is there a way to tune the kernel/scheduler settings in a way
    to get a higher read throughput? Writes are not that important,
    basicially there are only two 30 GB files on the device/filesystem
    that are used to spool data for two LTO-4 tape drives. So I need a
    certain read speed to keep both drives streaming. While the data gets
    written to one file, I need at least 50 MB/s for reading from the
    other file and sent to the tape drive.

    Thanks, Ralf

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      Last update: 2009-06-16 18:11    [W:0.035 / U:0.828 seconds]
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