2 newbe questions of a general nature - Plan9

This is a discussion on 2 newbe questions of a general nature - Plan9 ; i was reading about jukeboxs & worm drives on the plan9 site. CD-R ~= WORM... so does the venti system allow you to use a recordable cd in a multi- session mode as a backup repository? also, i am three ...

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Thread: 2 newbe questions of a general nature

  1. 2 newbe questions of a general nature

    i was reading about jukeboxs & worm drives on the plan9 site. CD-R ~=
    WORM...
    so does the venti system allow you to use a recordable cd in a multi-
    session mode as a backup repository?
    also, i am three hours into a fresh plan9 download, and firefox says i
    have three hours to go. ( i;m in the boonies about 5 miles past the
    nearest broadband, but i really want to try abaca badly. Maybe i can
    recycle my w98 partition!) isn't there a way to keep a plan 9 arena
    on the web so people who enjoy life on the bleeding edge could update
    their source from the incremental backup and rebuild rather than
    download a new iso to stay up to date?

  2. Re: [9fans] 2 newbe questions of a general nature

    On Wed Apr 4 05:14:54 EDT 2007, vlholmesjr@netzero.net wrote:
    > i was reading about jukeboxs & worm drives on the plan9 site. CD-R ~=
    > WORM...
    > so does the venti system allow you to use a recordable cd in a multi-
    > session mode as a backup repository?


    the worm was originally used with the standalone fileserver kernel.
    magnetic disks were used as cache, the dump (archival snap in
    venti-speak) was written linearly onto the worm starting at block
    3 of the first worm disk. a robot changer was used to swap disks.

    one could add the ability to write to cd/dvd to fs without too much
    trouble. the trouble is it takes a lot of dvds to backup a single drive
    and to make this really work, you'd need a robotic changer.

    venti has isect (index) and arenas (data). arenas are approxminately
    cd size, but there's no provision to deal with cds directly. copying
    filled arenas to cd would be pretty simple with cdfs. (dvds aren't
    supported. i don't know about muti-session cds.) the problem is
    making this automatic.

    > also, i am three hours into a fresh plan9 download, and firefox says i
    > have three hours to go. ( i;m in the boonies about 5 miles past the
    > nearest broadband, but i really want to try abaca badly. Maybe i can
    > recycle my w98 partition!) isn't there a way to keep a plan 9 arena
    > on the web so people who enjoy life on the bleeding edge could update
    > their source from the incremental backup and rebuild rather than
    > download a new iso to stay up to date?


    been there, done that! you can update with /usr/genda/bin/rc/pull.
    this will scan a log and update only the files changed. it was very
    speedy for me over a 56k modem.

    over the modem i never could get the full image to download before
    it was updated, thus forcing me to start over.

    - erik

  3. Re: [9fans] 2 newbe questions of a general nature

    > been there, done that! you can update with /usr/genda/bin/rc/pull.
    > this will scan a log and update only the files changed. it was very
    > speedy for me over a 56k modem.


    http://plan9.bell-labs.com/wiki/plan...ng_up_to_date/

    > over the modem i never could get the full image to download before
    > it was updated, thus forcing me to start over.


    I have heard various reports of people with broken ISO images and this
    might be an explanation.

    Would be nice if the BL overlords could avoid this, maybe by moving
    the previous day ISO before the new one takes its place, similar to
    how replica moves foo to _foo.

    uriel

  4. Re: [9fans] 2 newbe questions of a general nature

    > Would be nice if the BL overlords could avoid this, maybe by moving
    > the previous day ISO before the new one takes its place, similar to
    > how replica moves foo to _foo.


    It already does that (maybe the overlords aren't as dumb as you think).
    But if the HTTP download gets interrupted after a new file has been
    dropped in its place, a client retrying the HTTP request will see
    the new file. If your download is not interrupted, then it will get
    a consistent file.

    Even if you are getting interrupted, the CD is at most 100MB
    compressed, which is only 5 hours at 56kbps, so you've got plenty
    of time to grab it in the 24-hour window.

    Further, I doubt very much that this is the cause of people with
    broken ISO images. You can't get that far if you get half of one
    download and half of another. They're compressed, and the checksum
    will fail during decompression even if the web browser doesn't notice
    that the file changed in the second request. So you'd end up with a
    broken .bz2 file, not a broken image. If you ever get to a .iso file,
    it will be intact.

    Russ

  5. Re: [9fans] 2 newbe questions of a general nature

    russ,

    the plan 9 distribution is very nice and the careful work and thought
    that went into the distribution. i don't think there's anything stupid
    about it.

    however,

    On Thu Apr 5 11:13:00 EDT 2007, rsc@swtch.com wrote:
    > Even if you are getting interrupted, the CD is at most 100MB
    > compressed, which is only 5 hours at 56kbps, so you've got plenty
    > of time to grab it in the 24-hour window.


    i found that even with a 56k connection with compression
    (which works against you in this case), the download took significantly
    longer. modems can be difficult to keep connected. this in addition
    to the fact that i didn't know what time of day the new iso was cut,
    made it nearly impossible to download the iso.

    - erik

  6. Re: [9fans] 2 newbe questions of a general nature

    Ok, then I guess I was wrong.

    Maybe a solution to quanstrom's problem would be to use file names
    based on the creation date (one would only need to keep one or two
    around).

    uriel

    On 4/5/07, Russ Cox wrote:
    > > Would be nice if the BL overlords could avoid this, maybe by moving
    > > the previous day ISO before the new one takes its place, similar to
    > > how replica moves foo to _foo.

    >
    > It already does that (maybe the overlords aren't as dumb as you think).
    > But if the HTTP download gets interrupted after a new file has been
    > dropped in its place, a client retrying the HTTP request will see
    > the new file. If your download is not interrupted, then it will get
    > a consistent file.
    >
    > Even if you are getting interrupted, the CD is at most 100MB
    > compressed, which is only 5 hours at 56kbps, so you've got plenty
    > of time to grab it in the 24-hour window.
    >
    > Further, I doubt very much that this is the cause of people with
    > broken ISO images. You can't get that far if you get half of one
    > download and half of another. They're compressed, and the checksum
    > will fail during decompression even if the web browser doesn't notice
    > that the file changed in the second request. So you'd end up with a
    > broken .bz2 file, not a broken image. If you ever get to a .iso file,
    > it will be intact.
    >
    > Russ
    >


  7. Re: [9fans] 2 newbe questions of a general nature

    On 4/5/07, erik quanstrom wrote:
    > russ,
    >
    > the plan 9 distribution is very nice and the careful work and thought
    > that went into the distribution. i don't think there's anything stupid
    > about it.
    >
    > however,
    >
    > On Thu Apr 5 11:13:00 EDT 2007, rsc@swtch.com wrote:
    > > Even if you are getting interrupted, the CD is at most 100MB
    > > compressed, which is only 5 hours at 56kbps, so you've got plenty
    > > of time to grab it in the 24-hour window.

    >
    > i found that even with a 56k connection with compression
    > (which works against you in this case), the download took significantly
    > longer. modems can be difficult to keep connected. this in addition
    > to the fact that i didn't know what time of day the new iso was cut,
    > made it nearly impossible to download the iso.
    >


    what about setting up a bittorrent tracker ?

    it could solve the issue and allow to have several versions of the ISO
    available online for some time from various sources.

    --
    Laurent Malvert [laurent.malvert@gmail.com]

  8. Re: [9fans] 2 newbe questions of a general nature

    On Fri, Apr 06, 2007 at 03:26:19PM +0200, Laurent Malvert wrote:
    > On 4/5/07, erik quanstrom wrote:
    > >On Thu Apr 5 11:13:00 EDT 2007, rsc@swtch.com wrote:


    > >> Even if you are getting interrupted, the CD is at most 100MB
    > >> compressed, which is only 5 hours at 56kbps, so you've got plenty
    > >> of time to grab it in the 24-hour window.

    > >i found that even with a 56k connection with compression
    > >(which works against you in this case), the download took significantly
    > >longer. modems can be difficult to keep connected. this in addition
    > >to the fact that i didn't know what time of day the new iso was cut,
    > >made it nearly impossible to download the iso.

    >
    > what about setting up a bittorrent tracker ?
    >
    > it could solve the issue and allow to have several versions of the ISO
    > available online for some time from various sources.


    I'm sure you could even select from many already available ones.
    Just run a seed somewhere. Of course even that could be done
    unofficially and downloaders doing the checksum dance to verify
    the result.

    It would take load off the download servers, too, of course.

    For extra fashion points, you could have RSS feeds announce new
    versions. Many clients would let you follow those quite
    automatically.

    --
    To know what you prefer, instead of humbly saying Amen
    to what the world tells you you ought to prefer,
    is to have kept your soul alive.
    -- Robert Louis Stevenson

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