[OpenAFS] Newbie questions

[Derek Atkins]

Brian Akins <bakins@web.turner.com> writes:

> On Thu, 2003-07-03 at 17:47, Derek Atkins wrote:
> > 2. What happens to a client if it looses network connectivity to all
> > servers (file, database)?  Can it still use the data in its local
> cache?
> 
> > No.  It will eventually time out and the cache becomes invalid.  All
> > accesses to /afs will timeout.
> 
> Can you define "eventually?"  What I want to guard against is that a
> network blip isolates a group of clients for 5 minutes or so.  Is this
> timeout configurable?  Anyone have experience tinkering with this?

Unfortunately, no.  It's going to be somewhat random based on where you 
are in your "retry" clocks when the network outage hits.  It's also going
to depend on how the network goes down.

What do you mean by "blip"?  If the next goes down for 10 second, it's
not going to do anything to your clients.  If it goes down for 10
minutes your clients WILL time out.  The cutover is somewhere in
between (and again depends on what kind of outage it is).

> > MIT does it; the MIT/Athena archicture is all about dataless clients.
> > When there is a problem, just re-install to a known configuration.
> > All user data is stored in AFS.  Do you have specific questions?
> 
> 
> These "clients" would really be web servers, so they would be single
> purpose, so to speak.  Any links available explicitly using linux and
> openAFS is a "dataless" design. google didn't turn up much.

There's really nothing special about running in a "dataless"
environment.  Web servers are particularly easy, because you don't
have to deal with user logins.

> > > We are inverstigating using Linux (Redhat 7.2 and Debian 3.0).  If this
> > > goes well, we will continue with Solaris 8 & 9.
> > 
> > I would advise against 7.2 -- at least use 7.3.  RH7.3 was released in
> > April '02 (vs. December '01), and has a lot of patches that don't
> > exist for 7.2.  FWIW, MIT uses 7.3 and Solaris 8, and is in the
> > process of upgrading to Red Hat 9 and Solaris 9.
> 
> Our linux installs are merely based on 7.2.  We have our own kernel and
> various other components...

Oh, well then you'll also have to be sure to build your own AFS module.
I'd still recommend at least upgrading to 7.3....

> Thanks for the time.
> 
> -- 
> Brian Akins <bakins@web.turner.com>
> CNN Internet Technologies

-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
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