aptitude install sg3-utils
sgp_dd bs=512 of=/dev/null if=/dev/sda bpt=1024 thr=8 count=20480000 time=1 dio=1

vhost1:/# sgp_dd bs=512 of=/dev/null if=/dev/sdb bpt=1024 thr=8 count=20480000 time=1 dio=1
time to transfer data was 100.739991 secs, 104.09 MB/sec
20480000+0 records in
20480000+0 records out

vhost1:/# sgp_dd bs=512 of=/dev/null if=/dev/sda bpt=1024 thr=8 count=20480000 time=1 dio=1
time to transfer data was 97.226045 secs, 107.85 MB/sec
20480000+0 records in
20480000+0 records out

iscsi on /dev/sdb on vhost1 (above)
root@filer1:/archive1/realtmp/disktest# sgp_dd bs=512 of=/dev/null if=/dev/sda bpt=1024 thr=8 count=20480000 time=1 dio=1
time to transfer data was 150.609959 secs, 69.62 MB/sec
20480000+0 records in
20480000+0 records out


software raid 10 LA

vhost2:~# sgp_dd bs=512 of=/dev/null if=/dev/md1  bpt=1024 thr=8 count=20480000 time=1 dio=1
time to transfer data was 60.444795 secs, 173.48 MB/sec

                                                                                                      
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