I practiced NetBSD/pmax snapshot installation on my stock RZ25 SCSI disk,
and got a good result without major troubles.  I chose dd'ing-raw-write way
with a helper UNIX machine (Digital Unix) before attaching RZ25 disk with
my DS5000/33.

1. 32M-diskimage was dd'ed after I explicitely cleared the target RZ25
   disk with the helper machine (DEC3000/M300 allows users to erase SCSI
   disk with its PROM monitor command 'test scsi erase')
	
	DU# dd if=32M-diskimage of=/dev/rrz3c

   And Digital Unix happens to recognize NetBSD disklabel simply because
   DU uses the same labelling scheme.  DU's disklabel command showed;
	
	DU# disklabel -r rz3
--
# /dev/rrz3c:
type: SCSI
disk: fu2263sa
label: 
flags:
bytes/sector: 512
sectors/track: 53
tracks/cylinder: 15
sectors/cylinder: 795
cylinders: 1648
total sectors: 1312344
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0 

8 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:    65536        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 82*)
  b:   131072    65536    4.2BSD      512  4096    16   # (Cyl.   82*- 247*)
  c:  1312344        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 1650*)
  d:   512000   196608    4.2BSD     1024  8192    16   # (Cyl.  247*- 891*)
  e:   409600   708608    4.2BSD     1024  8192    16   # (Cyl.  891*- 1406*)
  g:  1148504        0    unused     1024  8192         # (Cyl.    0 - 1444*)
  h:  1148504        0    unused     1024  8192         # (Cyl.    0 - 1444*)
--
   This is an 'imaginary' disklabel in 32M-diskimage pretending to have
   such SCSI parameters.

2. RZ25 was moved, and attached with my DS5000/33.  It could boot
   DS5000 without any glitch with;
   
    	>>boot 3/rz3/netbsd

   Then I made the root filesystem writable with;
   
    	# mount -u -w /dev/rz3a /

3. Now it's time to adjust the RZ25 disklabel to reflect the realities.
   I extracted the 'imaginary' disklabel into a file '/LABEL' and edited
   it with 'ed' (Yes, I love it!)
   
   	# disklabel -r rz3 >/LABEL
	
   I placed rz3d and rz3e right behind the end of swap area for /usr and
   /var respectively.  /LABEL contents is now; 
--
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:    65536        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 117*)
>>b:   131072    65536      swap                        # (Cyl.  117*- 352*)
  c:   831978        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 1490)
  d:   584592   196608    4.2BSD     1024  8192    16   # (Cyl.  352*- 1399*)
  e:    50778   781200    4.2BSD     1024  8192    16   # (Cyl. 1400 - 1490)
--   
   Please note that I preserved original offset and extent values at the
   lines marked with '>>'.
   
   I succeeded in installing the new disklabel with;
   
   	# disklabel -r -R /dev/rrz3a /LABEL
   
4. 'newfs' on /dev/rrz3d and /dev/rrz3e, and 'mount' them /usr and /var
   respectively.   

5. Whole set of snapshot was placed on an NFS server.  I made proper
   network interface initialization with 'ifconfig,' and then do 'mount_nfs'
   remote directory on /mnt.
   
6. Files were extracted from snapshot distribution;

   # cd /	
   # for i in <the tar.gz files on /mnt directory>
   > do
   > tar --unlink --extract --ungzip --preserve --file $i
   > done

   Whole things were populated appropriately (including /dev. happiness..)

	[ someone knowledgeful, are these flags completely OK? ]
   
7. Adjust and configure important files in /etc directory.  /etc/fstab
   is important.  Other things have to be cared, but they could be tackled
   later.

8. To check things have well done DS5000 was rebooted.  In a fresh single
   user mode I tried to mount file systems;
   
   	# mount -a

   'df' command showed; 	
--
Filesystem  1K-blocks     Used    Avail Capacity  Mounted on
/dev/rz3a       31503    18648    11279    62%    /
/dev/rz3d      282246    85930   182203    32%    /usr
/dev/rz3e       24460      178    23059     1%    /var
-

After this moment everything can be done in 'Unix way' at will.

Although my experience is just a case which worked for me, I hope
above can help some. 

Tohru Nishimura
Nara Institute of Science and Technology