This is with a ridiculously old disk (third party Sun shoebox, ESDI 180MB and
Emulex SCSI-ESDI converter. Though I've to say that there was a label on that
disk, albeit one from that mythical 'dump filesystem via dd' on the disk...
So, it rather looks like some pecularities with the disk drive, then...
On the other hand I just discovered that I still have that old rootimage and
'makedisk' in source... 3MB and 10KB gzipped.

>> NetBSD INSTALLATION HP9000/345/375/400 CPU
>> $NetBSD: sys_inst.c,v 1.3.6.1 1996/09/11 18:00:32 thorpej Exp $
>> Available commands:
>>     disklabel - place partition map on disk
>>     miniroot - place miniroot on disk
>>     boot - boot from miniroot
>>     reset - reset the system
>>     help - display command list
sys_inst> diaklabel
unknown command: diaklabel
sys_inst> disklabel

You will be asked several questions about your disk, most of which
require prior knowledge of the disk's geometry.  There is no easy way
for the system to provide this information for you.  If you do not have
this information, please consult your disk's manual or another
informative source.

Disk to label? sd0
Sucessfully read 512 bytes from sd0
(z)ap, (e)dit, (s)how, (w)rite, (d)one > s

disk type 4 (SCSI), M2246: 
interleave 1, rpm 3600, trackskew 0, cylinderskew 0
headswitch 0, track-to-track 0, drivedata: 0 0 0 0 0

bytes/sector: 512
sectors/track: 35
tracks/cylinder: 10
sectors/cylinder: 350
cylinders: 820

7 partitions:
     size   offset
a:   30800,    350
b:   65800,    31150
c:   277550,    0
d:   0,    0
e:   20300,    96950
f:   0,    0
g:   160300,    117250

(z)ap, (e)dit, (s)how, (w)rite, (d)one > w
Sucessfully wrote label to sd0
(z)ap, (e)dit, (s)how, (w)rite, (d)one > w
Sucessfully wrote label to sd0