Wondering if anyone has researched the same issue I'm having or has a best practices list. I have a Cisco UCS platform which is not production yet, so just me doing testing. It has multiple ten gig links to redundant fabrics in end host mode. Those each have ten gig links to a pair of 4900M's. An EMC CX4-480 also has multiple 10 gig links to the same pair of 4900M's. The UCS blades are running vmware esxi 4.1 enterprise plus and EMC powerpath multipath I/O software. The storage is on a dedicated vlan and each end is tagging to it, no routing involved.
>From a guest running redhat 5 with vmware tools and a paravirtualized scsi adaptor, I can't seem to do better than about 250 MB/sec reading or writing over iscsi. I have tried all MTU's the EMC supports between standard and 9000 but I get nearly the same results except at 9000 byte where it actually gets a bit slower. Not that 250 MB/sec is bad, but I was expecting to hit 400 MB/sec running benchmarks since the EMC drive enclosures are 4gig FC attached and it has 8 GB of cache memory with no other activity on the system other than my testing. I should add that I have no issues having two virtual machines on different IP ranges, different UCS chassis and different blades talk to each other using network benchmarks at nearly 10 gig wire speed, and that's traffic that has to leave the cluster, go to the 4900's and come back down since we're running end host mode. So it's not a connectivity/4900 issue as far as I can tell. I notice a regular increase in pause frame count on the EMC interface of the 4900's which made me think maybe the EMC is lacking in buffers on the ten gig card? Would enabling/disabling a non-default flow control help? I've tried both on and off for tcp delayed ack on the vmware side. Thanks, David _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/