Due to limitations in Openboot PROMs, you can't boot any of the 32bit
SPARCs (sun4c, sun4m, sun4d) from a root partition that has parts lying
beyond the 2GB mark on a SCSI disk.
On systems with really old PROMs (revision 2.5 or less) you need to
make the root partition smaller than 1GB.
The Ultra PROMs are capable of this, but Solaris prior to version 2.6
also has a bug which effectively prevents Ultras from booting from
large root partitions too. Patch 103640-08 or later fixes this
for Solaris 2.5.1, so later 2.5.1 HW releases should be OK too.
Typical error messages include:
bootblk: can't find the boot program
boot: cannot find misc/krtld
Short read. 0x2000 chars read