[9fans] fossil+venti backup question - Plan9

This is a discussion on [9fans] fossil+venti backup question - Plan9 ; From time to time i get back to plan9 and starting fiddling with it, now i might found a reason to make it useful where i work.. If i understand correctly, venti uses fossil as a write buffer for today's ...

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  1. [9fans] fossil+venti backup question

    From time to time i get back to plan9 and starting fiddling with it,
    now i might found a reason to make it useful where i work..
    If i understand correctly, venti uses fossil as a write buffer for
    today's modifications, and if i want to access data in previous week's
    state, then files are served by venti.
    Or (as i read in plan 9 intro pdf): "In some cases, a single file server
    may provide more than one file tree. For example, the file system
    program used in Plan 9, fossil, makes a snapshot of the entire file tree
    each day, at 5am,
    and archives it for the posterity. It archives only the changes with
    respect to the last archive, but
    provides the illusion that the whole tree was archived as it was that day."

    What id like to know is:
    can i simply use fossil or do i need fossil+venti?
    can backup period (currently daily) be set to stg. else? Like every two
    hours?




  2. Re: [9fans] fossil+venti backup question

    > What id like to know is:
    > can i simply use fossil or do i need fossil+venti?


    Yes, but then you wont have permanent snapshots, I very much recommend
    using venti, among other reasons because even in case of your fossil
    getting corrupted (which is not unheard of, specially if you run out
    of space), you can always restore the last snap from venti.

    > can backup period (currently daily) be set to stg. else? Like every two
    > hours?


    Yes, see fossilcons(8), in particular the snaptime command, but you
    probably should read the whole man page to get a better idea of how
    things work.

    Best wishes

    uriel

  3. Re: [9fans] fossil+venti backup question

    On Thu Mar 29 07:05:00 EDT 2007, bituman@enerla.net wrote:
    > From time to time i get back to plan9 and starting fiddling with it,
    > now i might found a reason to make it useful where i work..
    > If i understand correctly, venti uses fossil as a write buffer for
    > today's modifications, and if i want to access data in previous week's
    > state, then files are served by venti.


    fossil is not a proper cache. fossil uses venti for archival snapshots
    (this would be called a dump in ken's fileserver). fossil is useful
    without venti. in fact, i think fossil without venti is better for a
    combined auth/cpu/fileserver as fossil is much kinder if you turn
    the machine off or hang it.

    the downside is if you do have a venti,
    > Or (as i read in plan 9 intro pdf): "In some cases, a single file server
    > may provide more than one file tree.


    this means you can connect to different file trees. so i can connect
    to kibbiee like this

    ; srv il!kibbiee kibbiee

    then mount the other filesystem, dump or main respectively

    ; mount /srv/kibbiee /n/other other
    ; mount /srv/kibbiee /n/dump dump
    ; mount /srv/kibbiee /n/kibbiee

    the 3d argument to mount is the "attach point". the server is free
    to choose a default, which for ken's fs is "main" and for fossil is "active".
    fossilcons(8) explains how to make different fossil filesystems. typically
    all you need is one.

    >
    > What id like to know is:
    > can i simply use fossil


    yes. you don't get archival snapshots without venti. you could
    use vac to roll your own.

    > or do i need fossil+venti?
    > can backup period (currently daily) be set to stg. else? Like every two
    > hours?


    you'd have to do this manually. you get one archive per day.

    - erik

  4. Re: [9fans] fossil+venti backup question


    > this means you can connect to different file trees. so i can connect
    > to kibbiee like this
    >
    > ; srv il!kibbiee kibbiee
    >
    > then mount the other filesystem, dump or main respectively
    >
    > ; mount /srv/kibbiee /n/other other
    > ; mount /srv/kibbiee /n/dump dump
    >

    ^^ this is exactly what id like to do
    to have a plan9 machine at work (which is the best way to learn plan9
    becouse my spare time is very limited and at work i am forced to play
    with it)
    i have to make good use to it. We need a file server (ftp server) with
    some decent backup features.
    I understand venti doesnt like unexpected reboots, but the machine will
    run 24/7 (if things dont turn nasty at our ISP)
    I thought about plan9 since i can serve current files, and can serve
    dumps at the same time.
    For this task then i will need fossil+venti right?
    Do you have any strong advice against using plan9 for this particular task?
    Can the hourly backup be done than? Im browsing through the man pages
    atm still reading..
    Having a daily backup and having todays backup modified every hour is a
    solution, but i would prefer backups for every hour if possible.
    Thank you in advance
    > ; mount /srv/kibbiee /n/kibbiee
    >
    > the 3d argument to mount is the "attach point". the server is free
    > to choose a default, which for ken's fs is "main" and for fossil is "active".
    > fossilcons(8) explains how to make different fossil filesystems. typically
    > all you need is one.
    >



  5. Re: [9fans] fossil+venti backup question

    On Thu Mar 29 07:12:11 EDT 2007, uriel99@gmail.com wrote:
    > Yes, but then you wont have permanent snapshots, I very much recommend
    > using venti, among other reasons because even in case of your fossil
    > getting corrupted (which is not unheard of, specially if you run out
    > of space), you can always restore the last snap from venti.


    the solution to fossil corrupting itself is to fix fossil, not to
    insist on venti.

    automatic archival snapshots are a great feature, but my personal
    experience has been that venti is not resistant to unexpected
    power failure.

    so i don't think that venti+fossil is a better solution than
    just fossil in every situation. not everyone has a dedicated
    fs on a ups.

    - erik

  6. Re: [9fans] fossil+venti backup question

    On Thu Mar 29 07:43:17 EDT 2007, bituman@enerla.net wrote:
    > to have a plan9 machine at work (which is the best way to learn plan9
    > becouse my spare time is very limited and at work i am forced to play
    > with it)
    > i have to make good use to it. We need a file server (ftp server) with
    > some decent backup features.


    what do you mean by "backup". are you interested in a historical
    perspecitive on file changes or are you worred about loosing data?
    if so, are you worried about a disk crash or are you worried about
    the machine burning up or the building falling down?

    - erik

  7. Re: [9fans] fossil+venti backup question

    > On Thu Mar 29 07:12:11 EDT 2007, uriel99@gmail.com wrote:
    >> Yes, but then you wont have permanent snapshots, I very much recommend
    >> using venti, among other reasons because even in case of your fossil
    >> getting corrupted (which is not unheard of, specially if you run out
    >> of space), you can always restore the last snap from venti.

    >
    > the solution to fossil corrupting itself is to fix fossil, not to
    > insist on venti.
    >
    > automatic archival snapshots are a great feature, but my personal
    > experience has been that venti is not resistant to unexpected
    > power failure.


    Besides the archival snapshots, the other nice feature of venti is the
    partitioning in CD-sized arenas. Having every used arena written to
    CD, one can stay quite calm, even if venti suffers a power failure.

    I write the latest arena onto CD in a daily cron job, periodically
    cmp'ing the CD set with the arenas.

    Heiko


  8. Re: [9fans] fossil+venti backup question

    erik quanstrom wrote:
    > On Thu Mar 29 07:43:17 EDT 2007, bituman@enerla.net wrote:
    >
    >> to have a plan9 machine at work (which is the best way to learn plan9
    >> becouse my spare time is very limited and at work i am forced to play
    >> with it)
    >> i have to make good use to it. We need a file server (ftp server) with
    >> some decent backup features.
    >>

    >
    > what do you mean by "backup". are you interested in a historical
    > perspecitive on file changes or are you worred about loosing data?
    > if so, are you worried about a disk crash or are you worried about
    > the machine burning up or the building falling down?
    >
    > - erik
    >

    The servers gonna be on 2 UPSes on different power circuits, but ISP
    staff seems to have a weird sense of humor, one time they simply pushed
    the power button on one of our servers.
    The place is supposed to be as safe as possible, and i'd like to have
    the data on mirrored raid discs.
    I am mostly worried about users deleting files etc..
    I need previous versions of files, and if the user by mistake deletes
    them, then i should be able to restore them.


  9. Re: [9fans] fossil+venti backup question

    On Thu Mar 29 08:07:40 EDT 2007, bituman@enerla.net wrote:
    > The servers gonna be on 2 UPSes on different power circuits, but ISP
    > staff seems to have a weird sense of humor, one time they simply pushed
    > the power button on one of our servers.
    > The place is supposed to be as safe as possible, and i'd like to have
    > the data on mirrored raid discs.
    > I am mostly worried about users deleting files etc..
    > I need previous versions of files, and if the user by mistake deletes
    > them, then i should be able to restore them.


    you can get sort-of mirrored raid with fs(3). it will
    behave differently from a typical raid device.
    intraspection of the device and no degraded state. also
    if you have a mirror of [m0m1] and [m0] fails, then reads
    will work but writes will fail. typical raid mirrors would
    report success in both cases but the raid would be put
    into a degraded state. also there's no support for rebuilding
    the mirror if you replace a disk. you need to do that by
    hand.

    while it's a bit different than you may expect, it might
    be fine for you.

    i think you could run without venti on a mirror of
    cat'ed disks (fossil wants a single partition.) by setting
    your snap time properly and allowing snapshots to
    live for a relatively long time (100 days). you could even
    periodicly take an archive with vac onto a venti, without
    depending on venti for day-to-day operations.

    your best bet is probablly fossil+venti.

    - erik

  10. Re: [9fans] fossil+venti backup question

    Heiko,

    * Heiko Dudzus [070329 14:07]:

    > Besides the archival snapshots, the other nice feature of venti is the
    > partitioning in CD-sized arenas. Having every used arena written to
    > CD, one can stay quite calm, even if venti suffers a power failure.
    >
    > I write the latest arena onto CD in a daily cron job, periodically
    > cmp'ing the CD set with the arenas.


    Could you please describe your setup to me? I am interested in that
    method.

    Thank you very much,

    Christian

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