"Keith" == Keith Brown keith@netapp.com writes:
>> Now I'm curious. >> >> If you have two filers clustered and with Gigabit NICs, then >> each filer has (at least) two Gigabit cards, with one card >> active and the second card being used only if a takeover >> occurs. >> >> In this situation, what would you need to do to have redundant >> NICs? Would you need a third NIC in each filer?
Keith> That.... is a very interesting fringe case! :-)
Keith> Candidly, I don't know for a *fact* if there is anything in Keith> our software to stop you trying to "re-use" the secondary Keith> gigabit interface in one cluster partner (the one that Keith> would take over from the primary gigabit interface from the Keith> partner if said partner should fail) as the secondary Keith> interface of an in-system single-mode trunk. However, I Keith> very much hope that there is, and I have no reason to Keith> believe that this case wasn't thought of by our network Keith> development team (some real smart folk).
Keith> Why do I hope that there is a barrier there? Well, Keith> obviously there is a rather-far-out-on-the-fringe case that Keith> could stop a cluster from failing over if you attempted Keith> such a stunt. Picture a gigabit card failing in one of the Keith> systems in a cluster, so the secondary interface of the Keith> single-mode trunk (in the same system) takes over from Keith> it. Now the partner server fails.... Where is its gigabit Keith> interface going to go on the survivor (which is down to its Keith> last NIC)? Oh dear....
Right. Which is why I assumed you would need a third NIC in each filer.
Keith> So in summary... don't do it. Not a good situation! ;-)
Well, I got into thinking about what you'd need for 100% redundancy. The filers are already highly redundant, but there are certain things that can fail that will cause downtime. Clustering two netapps eliminates the head (as a unit) as a single point-of-failure. If a NIC failed, you could always do a manual takeover. But I'd like to see something automatic. So that's how I got to wondering about redundant NICs in each unit in the cluster.
But now that we're off on this tangent... With a clustered netapp pair, what remains as a SPF? Do clustered shelves have any non-redundant components?
j. -- Jay Soffian jay@cimedia.com UNIX Systems Administrator 404.572.1941 Cox Interactive Media