Sunday, September 5, 2010

linux bonding does not double bandwidth

For 1G Nic, the maximum theoretical speed limit is 128MB/s.
In real world you get much lesser, adding the protocol overhead like we have scp, wget and other protocols.
If you are currently using mode 0.
In mode 0 there is chances for packet re-ordering. Which can delay the speed.
There may be slight improvement if you use mode 4.
With mode 4 the incoming connection is controlled by switch. So there will be no packet re-order issues or packet drops.
Even if you use mode 4, you cannot achieve 2G speed for a single connection. You can enjoy 2G bandwidth for multiple connections.

There is a assumption that configuration of bonding with multiple network cards gives double bandwidth. That is not at all true.

1 comment:

  1. surely the max is <= 125 MB/s, not 128. on correctly running systems I see a practical peak of about 117 MB/s.

    the real point of bonding speed is that it's normally link aggregation, not "link raid".