Here is my original posting to netbsd-users,
for which I did not receive any comments (question too stupid?!?!?) :

Hi list,
I got one of the 3ware escalade ide raid controllers with two
75 GB IBM DTLA drives attached and configured as RAID1.
NetBSD 1.6.1 sees a ld0 drive which a configure with
fdisk and disklabel.
But when I made the entries for /,/usr etc and it comes to
newfs sysinst stops and tells me I have to set bsize to 32768 and fsize =
to 8192.
If I do so, I can install and boot NetBSD but newfs tells me that the =
performance of the system can be degraded.
Is this a bug (twe driver), anything normal ?
P.S.:
It does not matter, if I enter the geometry by hand.