IPerf and windows copy

Hi,

Some of my backups were running slow, so i decided to use iperf to check network throughput. Between 2 windows systems (on the same switch) i got about 1-2MB. However, when i tried to copy some files from the on windows server to the other i got around 10-12MB. This is over a 1Gig link.

how is windows copy faster than iperf?

increasing tcp_windows_size in iperf to 1MB seems to have solved the problem