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    SubjectRe: Software RAID5 with 2.6.0-test
    Date
    In article <20031017192419.GG8711@unthought.net>,
    Jakob Oestergaard <jakob@unthought.net> wrote:

    | Now that I'm posting anyway - I thought of a plus for the HW RAID
    | controllers (hey, they're way behind on the scoreboard so far, so I
    | might as well be a gentleman and give them a point or two):
    | *) Battery backed write cache
    |
    | This will allow the controller to say 'ok I'm done with your sync()',
    | way before the data actually reaches the disk platters. For some
    | workloads this can be a big win.

    Unless the drives are battery backed up as well, I'm not sure that this
    is a good thing, or at least a safe thing. And if a write error happens
    after the controller tells you the sync() is done? That's a question,
    not a comment, I'm not sure Linux software RAID would relocate if the
    drive was out of spare sectors, either, but it at least could.

    I don't question your statement that caching helps performance, but I
    think there is some loss of reliability. I have no numbers to estimate
    the effect, so take it as a comment only.
    --
    bill davidsen <davidsen@tmr.com>
    CTO, TMR Associates, Inc
    Doing interesting things with little computers since 1979.
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