[OpenAFS] Optimizations

[ProbaNet - Info]

Hello guys!
    We're using openafs 1.6 fileserversand we would like to know if we
can do something to improve performance (we mean: parameters and values).
Scenario:
- 3 fileservers, all 64 bit KVM virtual machines with4 vCPU, 1280 MB RAM
and 4 x 250 GB vice partitions (which are iSCSI targets)
- 2 dbservers (1 sync site + 1 non-voting clone), 64 bit KVM vms, 2
vCPU, 512 MB RAM
- everything runs into an office LAN (1 Gbit), with around 40 users
- each fileserver hosts 200 to 600 volumes

Here's actual BosConfig for dbservers:
-----
restarttime 16 0 0 0 0
checkbintime 16 0 0 0 0
bnode simple ptserver 1
parm /usr/lib/openafs/ptserver -p 16
end
bnode simple vlserver 1
parm /usr/lib/openafs/vlserver -p 16
end
-----

Here's actual BosConfig for fileservers:
-----
restrictmode 0
restarttime 16 0 0 0 0
checkbintime 16 0 0 0 0
bnode fs fs 1
parm /usr/lib/openafs/fileserver -L -udpsize 65536 -cb 600000 -rxpck
4000 -vattachpar 8 -realm XXX.YYY
parm /usr/lib/openafs/volserver -p 16 -udpsize 65536
parm /usr/lib/openafs/salvager -parallel all4 -orphans remove
end
-----

Everything works quite fine (except for some occasional slowdown when
accessing some volume for the first time), but we would like to know if
we can do something to improve it! :) Thank you very much!

Stefano
Fabio

P.S.: we don't understand the difference between "-udpsize" and
"-sendsize" fileserver parameters: please can you explain it a bit? :)
Thanks!