"Imagine that you have a storage server connected to a switch by 4 1Gb Ethernet cables and the switch is using LACP (standard protocol for link aggregation) to form a LAG. You've also bonded the 4 NIC's on the storage server to act as one. Now imagine that you have a database server connected to the SAN for storage, also connected via 4 NIC's. Boom, 400MB/s right? Kind of, but not really."