[OpenAFS] Re: Server disk operations speed

Andrew Deason adeason@sinenomine.net
Tue, 9 Apr 2013 14:43:56 -0500

On Tue, 9 Apr 2013 21:55:40 +0300 (EEST)
"Jukka Tuominen" <jukka.tuominen@finndesign.fi> wrote:

> One thing I noticed immediately was that by disconnecting the server
> machine's NIC (VM though), I couldn't reach /afs/ contents any more,
> even if the machine contains all servers (services) and a client. Is
> that the expected behaviour?

The client contacts the VLDB through the IP address listed in your
CellServDB (or via AFSDB or SRV records in DNS). The client contacts the
fileserver via the IP addresses the fileserver detects at startup
(roughly), or what's in the server's NetInfo file.

So, if that machine can't reach that IP when the NIC is disconnected,
then yes, that's expected. If you just want to see where the traffic is
going, capture some net traffic. All AFS traffic for a client
interacting with a server should happen on ports 7000-7003 UDP. If we're
contacting an IP that is one of the local host's interfaces, it's up to
the underlying OS where the packets physically go.

And just by the way, I think it's probably a much better use of your
time to look at the data flow and try to see bottlenecks than just
fiddling around with server/client parameters. You don't really know
what parameters could change anything (if you change every single
runtime switch, you're going to be testing things for a while), and you
don't even know if the performance bottlenecks are anywhere in the
openafs software.

Andrew Deason