which mirror balance algorithm to use?

[OxY]

hi!

my box is a file server, it has about ~100-150 simultaneous connection
all the time, so the disks are very busy..
i'd like to use the best performance balance algorithm to reduce disk 
load, which is about 80-90% now..
which one should i use? 'load' and 'round-robin'?
why?

i tried to read something about this topic, did goole, so on, no result..

thanks a lot for all your help!