Re: [9fans] ata drive capabilities - Plan9

This is a discussion on Re: [9fans] ata drive capabilities - Plan9 ; > i don't know. if you lean that direction, then the only thing raid > gives > you is reduced downtime. On reflection, it seems I do lean that direction, and generally use raid mainly to dodge downtime. Our plan ...

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Thread: Re: [9fans] ata drive capabilities

  1. Re: [9fans] ata drive capabilities

    > i don't know. if you lean that direction, then the only thing raid
    > gives
    > you is reduced downtime.


    On reflection, it seems I do lean that direction, and generally use
    raid mainly to dodge downtime. Our plan 9 systems (and `other' alike)
    mostly have redundant disks (when they must have them at all) -- but
    they have regular offsite backup also. I wonder if I'm being wasteful.

    > i think of raid as reliable storage. backups are for saving one's
    > bacon in
    > the face of other disasters. you know, sysadmin mistakes,
    > misconfiguration,
    > code gone wild, building burns down,
    >

    meteorite!

    > (and if my experience with backups is any indiciation, it's best
    > not to
    > rely on them.)
    >

    Probably another discussion, but I try to deal with this by testing
    the offsite backups (rdarena output) of the plan9 fileserver against
    a similar system that's designated the second-string fileserver. I
    haven't had to do it in production in a while, (raid narrowed the
    reasons I'd need to) so maybe I'm missing something and it would be
    less successful than in the testing.

    > but this thinking is probablly specific to how i use raid. i
    > imagine the
    > exact answer on what raid gives you should be worked out based on
    > the application.
    >

    I probably veer toward mere semantics, but I'd still define your use
    of raid to be uptime-protection. The list of exceptions you place
    under ``backups are for...'' is the same list, essentially, that
    motivates the offsite backups I mention -- the usual holes in the
    raid prophylactic. I see how Plan 9 facilities (esp. dump) ameliorate
    some of them: admin mistakes, for example. But it doesn't fireproof
    the system.

    Or, put another way, you're not asserting you have no backup beyond
    that fileserver raid, are you? Because if so, I want to learn how I
    can skip that step, too.

    --
    Josh





  2. Re: [9fans] ata drive capabilities

    >
    > Or, put another way, you're not asserting you have no backup beyond
    > that fileserver raid, are you? Because if so, I want to learn how I
    > can skip that step, too.
    >


    here's what we do useing ken's fs fs, not venti.

    http://cm.bell-labs.com/iwp9/papers/23.disklessfs.pdf

    - erik

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