Re: Yet another infrastructure problem

On Saturday 25 October 2008 04:23:34 Magnus Hagander wrote:
> Stefan Kaltenbrunner wrote:
> >> * One way around problems like this is to mirror the services.
> >> That may involve load balancing, DNS tricks, database replication,
> >> and other assorted goodies. It may be difficult, but it's something
> >> I'd like to at least start us talking about.
> >
> > the low hanging fruit in that regard has already been taken (have you
> > seen the static part of website being down in the last few years?) -
> > most of the other services are much much harder to operate in a
> > loadbalanced (or master-master) setup or doing it seems simply overkill.
> > Furthermore I don't think that just making services more complex (as in
> > redundant) will necessarily result in better availability. Howver I
> > aknowledge that we can improve in some areas (like wiki authentication).
>
> I think the most important thing to get a workaround for is our mirror
> management. Because now if wwwmaster goes down, nobody can download our
> stuff from the website - even if both the webside and 100 ftp servers
> are up.
>
> Now, getting that one done shouldn't be too hard. Since the data is
> really only one-way (I don't mind if we loose click-thru stats). So we
> can either:
>
> 1) replicate the mirror database to a secondary jail somewhere, running
> the wwwmaster code. Link the downloads to a separate DNS name that maps
> to both these machines, and does checking similar to our static machines
> to remove them from DNS if they go down.
>
> 2) reimplement the mirror management stuff in client-side javascript
> somehow, and serve it off the static mirrors. Not entirely sure how to
> do this cleanly, or how to fallback if $user has javascript disabled,
> but it would have the advantage of not needing another jail.
>
>
> My vote would be for #1 here, as I think is clear.
>
>
>
> The login system would also be good to have distributed, but it's used
> by orders of magnitude less number of people. But if we replicate the
> database off to the other machine, it should be possible to point the
> logins on both machines as well - it's a simple pl/pgsql function that
> needs to be called. We'll just need to deal with the "last logged in"
> part that won't work then.
>

If you used plproxy rather plpgsql, i think you could eliminate this problem. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL