In message <200502252015.PAA01647@Sparkle.Rodents.Montreal.QC.CA> you write:

|> > Hmm, the kernel has to be in the first 2 or 4 GB if I remember
|> > correctly because old OBPs have such limits but that's not really a
|> > filesystem limit.

|> 1GB.  That limit comes about because the bootrom versions in question
|> always use only 6-byte CDBs, never 10-byte, and as a result have only
|> 21 bits of block number.  This means they are not capable of accessing
|> other than the first 2097152 sectors.

With SunOS 4, partition size was limited to 2 GB by (IIRC) mkfs/fsck/dump
using signed 32 bit integers for byte pointers into the character device.