about the top speed of Link Aggregation and A STRANGE PROBLEM

[bo wang]

Hi ：
   I use a dell server making Link Aggregation with 6 ports and make
it be a FTP server. When I use 2 pc  connect the server at  the same
time. The top speed of the server can be 200MB/S. And in the
transmission I cut off one of working ports,the discard connetion will
be use another working port , it can't use a free port. So the top
speed is down to 100MB/s. And I use 2 pc connect again, It stil use
the last port. So I cut it off. Something happens,it will use 2 free
ports.And the top speed is up to 200MB/s. What is the matter? And I
use 3 pc connect,they use 3 ports. I cut one of them.It will use
another working port. Now there are two working ports,3 free ports,1
cut off.When I cut another port, It will use 2 free ports.Now it turn
back for using 3 ports, Why ?The LACP protocol's problem?
    And I have a another question. I make RAID 0 in my server , Why
the top speed is 200MB/S ?  and  how could I do can make 2 server
transport with Link Aggregation ?