To install initial disklabel on RZ25, try this way;

# disklabel -R -r rz2a INITAL_LABEL
                  ==== seems OK with "/dev/rrz2a", either.

It ran well with my NetBSD/pmax. (not one which runs on ULTRIX, sorry)

My label content is as follows (result of disklabel -r);

# /dev/rrz0c:
type: SCSI
disk: DEC RZ25
label: 
flags:
bytes/sector: 512
sectors/track: 62
tracks/cylinder: 9
sectors/cylinder: 558
cylinders: 1491
total sectors: 831978
rpm: 4412
interleave: 1
trackskew: 7
cylinderskew: 26
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0 0 0 0 32147 

8 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:    66960        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 119)
  b:   122760    66960      swap                        # (Cyl.  120 - 339)
  c:   831978        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 1490)
  d:   591480   189720    4.2BSD     1024  8192    16   # (Cyl.  340 - 1399)
  e:    50778   781200    4.2BSD     1024  8192    16   # (Cyl. 1400 - 1490)

--

It's very nasty that disklabel occationally complains even without
any apparent reasons.  Here is the type-script when I tried above.
I did this after explicitely clearing disklabel area of the drive with
OSF/1 disklabel -z command.

<boot NetBSD/pmax with single user mode>

  # disklabel -r rz0
  rz0: WARNING: no disk label
  label: 0
  rz0: WARNING: Ultrix labek, no disk label
  disklabel: no disk label
  # disklabel -r rz0
  disklabel: no disk label
  # disklabel -r -R rz0 /LABEL.rz25
  disklabel: DIOCSDINFO: Open partition would move or shrink
  # disklabel -r -R /dev/rrz0c /LABEL.rz25
  disklabel: DIOCSDINFO: Open partition would move or shrink
  # disklabel -r -R rz0a /LABEL.rz25
	!!! DID WORK AT LAST !!!

Tohru Nishimura
Nara Institute of Science and Technology