I was experimenting with using channel bonding my twin eth ports to get a combined bandwidth of (close to) 2 Gbps. The two relevant modes were 4 (802.3ad) and 6 (alb=Adaptive Load Balancing). I was trying to compare performance for both.
Before running any sophisticated tests by netperf etc. I just tried to copy a large file via scp and timed the two file-copies. Option1: from node1 to node2. Both nodes have their twin ports bonded together as bond0 with mode=4 (802.3ad). They are connected via a Dell PowerConnect 6248 switch. Configured the switch so that I have two LAG groups combining the two ports coming from the same node. LACP was turned on. Option2: from node3 to node4. Use mode=6 (alb=Adaptive Load Balancing) No special switch config. No LAG. No LACP. Result: For a 4GB file-transfer. Both modes took the same time; approx 1min26 sec. These results are very mystifying to me. I was expecting mode4 (802.3ad ) to be almost twice as fast since it is the only mode which truly aggregates the twin channels. It ought to be the only one effective for a peer-to-peer communication (mode 6 would only help while talking with more than one peer) Any comments? Also the net file transfer speed seems way lower than what I'd expect from a close to 2 Gbps connect; even accounting for the protocol overheads. Do other people have some numbers for me from their systems? -- Rahul _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
