I have a CentOS server set up with Samba on a gigabit LAN connection. I've found that if I copy large amounts of data from the Samba server to a client machine that also has a gigabit connection, that one file copy process completely eats up Samba's attention. Sometimes I can't even get a share listing on another computer while the copy is going.
Is there a way to set up some sort of QoS on Samba so that multiple clients are forced to share the bandwidth/whatever-samba-is-limited-on and be nice to each other?