ggate + gmirror write performance woes

[Sven Willenberger]

I am trying to set up a HA type system involving two identical boxes and
have gone through the following to set up the systems:

Slave server: 
ggated -R 196608 -S 196608
(exporting /dev/amrd1 )
net.inet.tcp.sendspace: 65536
net.inet.tcp.recvspace: 131072



Master server:
ggatec create -u 0 -R 196608 -S 196608 -o rw [slaveip] /dev/amrd1
net.inet.tcp.sendspace: 131072
net.inet.tcp.recvspace: 65536


#gmirror status
      Name    Status  Components
mirror/gm0  COMPLETE  amrd1s1
                      ggate0s1

the two servers are connected to each other via their 2ndary physical
gigE interfaces using cat6 crossover cable. (Netperf shows 890 Mbps at
95% confidence).

softupdates are enable on gm0 (though this does not affect the results).

The results:
/usr/bin/time -h cp testfile64M /data1
        28.62s real             0.00s user              0.16s sys

and this is very consistent ... about 3 MB/s over repeated runs 

dd if=/dev/zero of=/data1/testfile32M2 bs=32k count=1024
1024+0 records in
1024+0 records out
33554432 bytes transferred in 16.122641 secs (2081199 bytes/sec)

What else can I tune here to make this functional? If I increase
recvspace and sendspace much beyond those numbers, ggated will not start
claiming to not have enough buffer space.

Sven