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    SubjectRe: questions about io scheduler
    Timothy Miller wrote:
    >
    >
    > Mike Fedyk wrote:
    >
    >> Nick Piggin wrote:
    >>
    >>>
    >>>
    >>> Kyle Wong wrote:
    >>>
    >>>> 2. Does io scheduler works with md RAID? Correct me if I'm wrong,
    >>>> io-schedular <--> md driver <--> harddisks.
    >>>>
    >>>>
    >>>
    >>> It goes md driver -> io schedulers -> hard disks.
    >>
    >>
    >>
    >> There is an IO scheduler per disk.
    >>
    >> So MD submits the data to each disk through the IO scheduler.
    >>
    >> This allows you to have the heads on each disk in the array at
    >> different locations, and helps keep response times lower for seeky loads.
    >
    >
    > Say you've got a RAID1. In this case, MD could send the read request to
    > either device. How does it decide which one to use?

    The one with the drive head closest to the data.
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