From: Conor Daly (conor.daly at domain met.ie)
Date: Tue 14 Aug 2001 - 14:56:04 IST
On Tue, Aug 14, 2001 at 12:04:04PM +0100 or thereabouts, Niall O Broin wrote:
> On Tue, Aug 14, 2001 at 10:02:38AM +0000, Conor Daly wrote:
>
> > > IEP1600 for dual PIII 800MHz, 1Gb RAM, 2x 40Gb IDE
> > > IEP700 for switches, client NICs and cabling
> >
> > IEP1600 will also get two:
> >
> > Athlon 1GHz, 512MHz, 40Gb IDE
>
> which IMHO will be a better solution for the money which is presumably, in
> this situation, tight. When everything's nominal, you've got more going for
> you than the dual processor scenario, and if one server goes down everything
> continues to operate, albeit a little more slowly. There will be work to be
> done to make it smooth for the unskilled operator, but for instance, the
> server which is normally an NFS client could be configured so that it looks
> for its NFS server on boot and if it finds it, mounts the remote home
> directory, otherwise it just mounts the local copy. There is some small
> danger of things getting out of sync if e.g. the servers go down due to a
> power outage - probably not uncommon in Malawi - and then are brought back
> up in the wrong order, but nice simple operational instructions should take
> care of that.
I'd be inclined to think that could be handled quite simply by the use of a
"live" flag. Machine A comes up and looks for machine B. If it doesn't
find it, it echoes its hostname into a "live-machine" file, NFS exports /home
and starts serving. Now machine B comes up, looks for machine A, finds it
and reads the "live-machine" file. B then does an rsync on machine A's
/home, looks for any "wrong way around" files and tries to push them up to
A. The difficulty arises when a file that was newer on machine B before the
reboot gets modified on A before B comes back up.
Conor
-- Conor Daly Met Eireann, Glasnevin Hill, Dublin 9, Ireland Ph +353 1 8064276 Fax +353 1 8064275 ------------------------------------ 1:18pm up 14:22, 9 users, load average: 0.05, 0.10, 0.03
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