I get disk read rates of only (at best) 40% of the
maximum theoretical rate on my VS4000/60 -

# dd if=/dev/rsd0c of=/dev/null bs=1024k count=100
100+0 records in
100+0 records out
104857600 bytes transferred in 40 secs (2621440 bytes/sec)


In fact, writing to the disk is faster:
# dd if=/dev/zero of=/dev/rsd0b bs=1024k count=100
100+0 records in
100+0 records out
104857600 bytes transferred in 36 secs (2912711 bytes/sec)

I find this rather odd.  Is there an explanation?

I just upgraded my VS4000/60 to 1.5_BETA2 (from 1.4X).
However, SCSI performance seems practically unchanged.

The disk is a fairly modern U2W drive:
asc0: NCR53C94, 25MHz, SCSI ID 7
scsibus0 at asc0: 8 targets, 8 luns per target
probe(asc0:1:0): max sync rate 6.25MB/s
sd0 at scsibus0 target 1 lun 0: <IBM, DNES-309170W, SAH0> SCSI3 0/direct fixed
sd0: 8748 MB, 11474 cyl, 5 head, 312 sec, 512 bytes/sect x 17916240 sectors

-aw