Hi Jon On Friday 05 February 2010 18:10:54 Jon Forrest wrote: > > This results in > > icmp_seq=2 Frag needed and DF set (mtu = 1500) > > which is not what I expected. I wonder where the > "mtu = 1500" is coming from. ifconfig on the interface > of the source machine is definitely 9000 (I just > reconfirmed). I also confirmed that jumbo frames > are enabled both on the switch and on the storage > server. They are. > > For yuks, I tried lowering the packet > size lower, and I found that I continued to see this > error until the packet size was 1472. So, either > ping is doing something I don't expect, or somebody > is lying about jumbo frames being enabled. >
That sounds that one component is not allowing jumbo frames through. > This is a 48 node cluster, so doing something like > that is something I'd like to hold off on doing > until I've exhausted everything else. 48 are easy, it starts to get interesting in the not too low 3 digit regime, 4 digits are more fun ;) What I would do next are the following routes (try both): Route A: Set MTU1500 everywhere and stress the system and look if the problems go away. Route B: (a) Directly link two nodes and try the ping again, if that does not work, there seems to be a problem with the nodes NICs. (b) Directly link a node a the 7340, try the ping again, if it does not work but (a) did, the 7340 is acting up. (c) Try the ping between two nodes with a single switch in-between and see if that works. Basically, start at the simplest set-up and work your way up the complexity ladder, it's tedious but eventually you'll find the problem. Cheers Carsten _______________________________________________ autofs mailing list [email protected] http://linux.kernel.org/mailman/listinfo/autofs
