Brian,

~     My question is what type of mirrorwrite has the least amount of
~     performance impact on the network?

probably not exactly what you want to hear:
very different results will be obtained in different environments
and for different requirements..
For me a hardware RAID solution was far and away the best
from some configurations tested.
Maybe more expensive on the begining,
this solution has paid itself back through reasonable  performance.


Juraj Salak