Solaris 9 on a Sparc 20
18 Gig Disk
Partitioning Scheme

I used a SUN18G disk (16.86Gb) disk partitioned as:
s0	/		1.95 Gb
s1	swap		1.08 Gb
s3	/patches	3.13 Gb
s4	/var		4.89 Gb
s5	/usr/local	3.13 Gb
s6	/usr/scratch	2.70 Gb

I was in fact able to load Solaris 9
on a sparc 20, both CD's. And it boots up and runs. Here's the latest
filesystem loading:

# df -k
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/dsk/c0t3d0s1    1982687 1309285  613922    69%    /
/proc                      0       0       0     0%    /proc
mnttab                     0       0       0     0%    /etc/mnttab
fd                         0       0       0     0%    /dev/fd
/dev/dsk/c0t3d0s4    5048230   27705 4970043     1%    /var
swap                 1109476      20 1109456     1%    /var/run
swap                 1109456       0 1109456     0%    /tmp
/dev/dsk/c0t3d0s3    3277530       9 3244746     1%    /patches
/dev/dsk/c0t3d0s5    4036062       9 3995693     1%    /usr/local
/dev/dsk/c0t3d0s6    1987399       9 1927769     1%    /usr/scratch
# 


And here's the partitioning scheme used:
partition> pri 
Current partition table (original):
Total disk cylinders available: 7506 + 2 (reserved cylinders)

Part      Tag    Flag     Cylinders        Size            Blocks
  0       swap    wu       0 -  438     1010.04MB    (439/0/0)   2068568
  1       root    wm     439 - 1306        1.95GB    (868/0/0)   4090016
  2     backup    wm       0 - 7505       16.86GB    (7506/0/0) 35368272
  3 unassigned    wm    1307 - 2719        3.17GB    (1413/0/0)  6658056
  4        var    wm    2720 - 4895        4.89GB    (2176/0/0) 10253312
  5        usr    wm    4896 - 6635        3.91GB    (1740/0/0)  8198880
  6        usr    wm    6636 - 7505        1.95GB    (870/0/0)   4099440
  7 unassigned    wm       0               0         (0/0/0)           0


Note that it even works with setting the swap to slice 0, vice 1
since by default with Solaris 9, this is how SUN would set it.

It's not the fastest, and the install takes several hours, my
guess would be between 4 and 6, but it does work.