>> There might be firmware limitations if your large drive is also your
>> boot drive.  I think that earlier firmware (PROM) version sun4u
>> machines can only boot from the first 4Gb of the disk, so your root
>> partition can't be larger than this.

That doesn't quite follow; see below.

> I think I have had 8 GB root fs (under Solaris 8|9|10) with the
> current OBP rev on U2s.  If it is really a life-and-death matter for
> anyone I could easily test it. :-)

It's not a matter of whether the boot partition is over the limit; it's
a matter of whether anything needed for booting is over the limit.
This seems like a subtle difference, but it's a critical one; you can
have a 100G partition, and, provided you can arrange that everything
needed for booting is below the limit, you're fine.  This is
significant largely because it can mean that a big partition can "work
fine" even if your machine has the limit - until you happen to do
something that puts (say) a new kernel that exists too far out on the
disk into place.  (This is not a hypothetical scenario.)

Also, check that 4G.  The usual limit with SCSI is 6-byte CDBs, and
that limit is 1G.  (There certainly could be a 4G limit, most plausibly
if something stupidly keeps 32-bit byte offsets somewhere, but Sun had
PROM access well beyond 4G working in the sun4m era; I can't see why
they would have broken it with the sun4u line.)

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