[arch-general] Making pacman check multiple repos

[Ng Oon-Ee]

On Sat, 2009-12-12 at 17:08 -0700, Brendan Long wrote:
> 2009/12/11 Ng Oon-Ee <ngoonee at gmail.com>
> 
> > On Sat, 2009-12-12 at 02:13 +0100, Heiko Baums wrote:
> > > Am Sat, 12 Dec 2009 08:58:17 +0800
> > > schrieb Ng Oon-Ee <ngoonee at gmail.com>:
> > >
> > > > Because sometimes all the mirrors listed in mirrorlist will not have
> > > > the file, if its just been uploaded. Also not everyone stays
> > > > up-to-the-minute with updates, judging by the "updated after a month"
> > > > posts we see once in a while.
> > > >
> > > > I'm concerned about the last bit, if a package was just uploaded and
> > > > only exists on one mirror, everyone who updates and has that package
> > > > in the period between its uploading and its appearance on their local
> > > > mirrors will 'fall-back' on varying mirrors (lengthening the update
> > > > process) and all end up on the poor main server (or Tier 1/2 mirrors).
> > > > Bad for both the mirror bandwidth as well as most probably much slower
> > > > for the user, who could probably just wait a day or so for the update
> > > > to come to his (faster, presumably) local mirror.
> > >
> > >
> > > Wouldn't it be possible to first upload the packages and update the db
> > > files when the packages on the mirrors (at least on several mirrors)
> > > are updated?
> > >
> > > If I have such a "problem" that a package is on no mirrors, which
> > > doesn't happen often, I usually abort the system update and wait one
> > > day. I think that's the normal and easiest way of solving this issue.
> > >
> > > Greetings,
> > > Heiko
> >
> > The few mirrors which sync first would have quite much higher bandwidth
> > usage =).
> >
> > The concern then is that in the period of time between uploading of
> > packages and updating of db, the db would point to a package (foo-1.3)
> > while the mirror would only have the new version (foo-1.4), since I
> > don't think many mirrors keep multiple copies of the same package
> > (schlunix I know off, any others?). So that would break updating as
> > well, just in a different direction, and this would not be recoverable
> > from.
> >
> >
> Maybe a better idea would be to make pacman keep track of the last time it
> got an updated package list, and if it's beyond a certain point, it starts
> checking other mirrors (maybe optional "No updates have been found in 5
> days, would you like to scan other mirrors for updates?").

The difference I would see is that in the current system an out-of-date
mirror is still use-able (no mismatch between db and package as we're
discussing). Some would manually change mirrors, but others would not,
so the net effect of automating fallover would be to increase load above
what it currently is.

Not everyone needs packages right on the day they're uploaded, or runs
pacman everyday (I do, though =p)