[OpenAFS] read/write replication

[Derek Atkins]

As has already been mentioned, AFS does not handle multiple read-write
volumes.  You can make read-only replicas of a single read-write
volume, but that is only really useful for centralized software
distribution.

I'm still trying to get a handle on the application you're trying to
use.  You say you want read-write volumes at all your sites -- that
seems to imply to me that all of your sites are different
administrative domains, which means to me that each site should
have its own AFS Cell.

You can then have a master cell that is used for cross-replication,
and a daemon that will automatically copy changes back and forth.
Unfortunately this isn't very automated nor is it very real-time.
Then again, neither is the Cloning process in generating RO replicas
of a RW volume.

Another issue with using RW/RO volumes together -- it's VERY difficult
to have site A use the RW and site B use the RO volumes of e.g.
user.warlord if both sites A and B are using the same cell.  The
reason is that mountpoints will cause the client to _ALWAYS_ use the
(single) RW volume, or _ALWAYS_ use the (multiple) RO volumes (if they
exist).

Good Luck,

-derek

Zachary Denison <zacharydenison@yahoo.com> writes:

> so using this, is there a way I could trick AFS into
> mirroring my volume to 5 different servers?
> 
> --- Derek Atkins <warlord@MIT.EDU> wrote:
> > Keep in mind that read/write'ness is on a per-volume
> > basis, not a per
> > server basis.
> > 
> > -derek
> > 
> > Zachary Denison <zacharydenison@yahoo.com> writes:
> > 
> > > Hi,
> > > 
> > > I am very eager to deploy an OpenAFS cluster.  We
> > have
> > > 5 different offices in different cities and I want
> > to
> > > create a large global filesystem so that each
> > office
> > > has its own local read/write AFS server and any
> > > changes made to it get immediately propagated to
> > all
> > > other AFS servers.
> > > 
> > > In reading the AFS documentation it seems that you
> > can
> > > only have one read/write server and the rest have
> > to
> > > be replicated read/only.  
> > > 
> > > Is there a way to do have multiple read/write
> > > replicas?  
> > > 
> > > If not, does anyone know a solution to this
> > problem?
> > > 
> > > -thank you
> > > Zachary
> > > 
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> > -- 
> >        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
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> 
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-- 
       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