[OpenAFS] two replicated servers

[matias morawicki]

Quoting Derek Atkins <warlord@MIT.EDU>:

> matias morawicki <mmora@barcala.ing.unlp.edu.ar> writes:
> 
> > Hi all, I'm trying to set up a two servers configuration with replicated
> > volumes. I want to be able offer the same resources (except homes) even if
> one
> > machine fails. 
> > I've both servers running normally with all volumes I want replicated, but
> I've
> > read in the documentation that with this configuration (two servers) Ubik
> may
> > fail if one of the servers is down, since the cannot elect the main server.
> Is
> > that correct or I've misread something? Is it possible to have such a
> configuration?
> 
> This is true.  The machine with the lowest IP address get's an extra
> half-vote in the quorum election, so if it goes down then you will
> lose quorum.  The fix is to run with three database servers, because 2
> > 1.5 (so even if your lowest-ip server goes down, you still have
> quorum).

you mean, three ptservers and three vlservers, right? All I need is another
machine running those services or I also need to run the fs? I'm asking because
I have an old router that might be the third server, but it doesn't have much
memory (pentium 100, 32MB RAM), so I don't want to load it too much. 

> 
> > Another thing. I'd like to have a semi-recent replica (one day old, one
> week
> > old) of the home directories in case the main server fails, even if it's
> a
> > read-only volume. I've been thinking that maybe it's possible to make a
> "vos
> > release" of them daily (at midnight for instance) and configure the clients
> to
> > "prefer" the main server (R/W volume) in normal situations. In this case,
> only
> > if the main server fails I can use the "old" and R/O copy of the secondary
> server. 
> 
> You can do that..  Just be sure that the user homedir mountpoint is
> specifically for the RW volume, otherwise it will decend into the
> RO volume and really confuse your users.  So, me sure you use the -rw
> option to fs makemount.
> 

I've already have the homedirs, and they were created with -rw. I've been
thinking about using "fs setprefs" on the clients to make them use the main
server when it's available. Is there anything else besides what's on the docs
that I should know? (like: is that rank saved or I have to set it again after a
reboot?) 
I have another question, if I want to do that, I mean, to daily or weekly
replicate homedirs, do I need a script to do the "vos release" for each volume,
or I can use wildcards like "vos release user.*" ?

thanks a lot

> > I'm all ears. Thanks a lot.
> > 
> > Matias Morawicki
> > Network Administrator
> > Facultad de Ingenieria
> > Universidad Nacional de La Plata
> 
> -derek
> 
> -- 
>        Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
>        Member, MIT Student Information Processing Board  (SIPB)
>        URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
>        warlord@MIT.EDU                        PGP key available
> 




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