Gluster users - Nov 2012 - performance issues of gluster

hi, all:

I'v got a Gluster testing, and found some performance issuse pertain to
Gluster
I built a ten-node Gluster enviroment, (3 X HP 380G5, 4 IBM 3650, 2 X HP C7000.
1 X DELL PE2950, all the network switch & NICs are all gigabit).

And set up three volumes:
	a ten-brick distribute volume (ten-brick means this volumes resides on ten
nodes, others are same),
	a five-brick distribute volume,
	a ten-brick distribute replica volume

And I copied a folder ( including about 100 files, the size of everyfile is
40MB~80MB) to these three volumes one by one, and found the average speeds are:
	to ten-brick distribute volume : 25MB/s
	to five-brick distribute volume: 50MB/s
	to ten-brick distribute replica volume: 10MB/s

Who have any idea about:

	Why the performance is so bad?
	Why the performance of ten-brick distribute volume is worse than
five-brick's(technically ten-brick volume should be better than five-brick
volume)?
	How to tune it?

Thanks

Tide Lui