gmirror

[vohand at gmail.com]

Hardware: SATA RAID adapter with SiliconImage 3114 chip. 2 SATA HDD.
I did gmirror.

Run test:
3 parallel tasks "dd if=/dev/mirror/gm0 of=/dev/null bs=1m count=5000"

gstat shows summary read speed from mirror about 30-40 mbyte/sec.
It is for all balance algorithms: load, round-robin, split

While, one "dd if=/dev/ad4 of=/dev/null bs=1m count=5000" shows 50 mbyte/sec

1. Why it occurs and how fix it ?

2. If in the test instead of three instancies of "dd if=/dev/mirror/gm0
of=/dev/null bs=1m count=5000" run only one, 
   then read speed don`t exceeds read speed from one disk (dd if=/dev/ad4
of=/dev/null bs=1m count=5000)
	a) This is gmirror feature ?
	b) This is hardware feature (SiliconImage 3114 chip) ?