Large filesystem woes

[dpk]

Has anyone here had any luck whatsoever getting FreeBSD 5.4-RELEASE to use
4TB of space from a 4TB RAID array? It is apparent that there is a
1TB/slice limit, and sysinstall doesn't seem to be able to handle creating
more than 2 slices.

I read somewhere that people recommend using "gpt" to manage large
filesystems. Unfortunately, this tool is not to be found on the fixit
floppy or the mfsroot during installation. If the server is up, gpt
complains about "Operation not permitted" because the disk is in use.

I managed to get "gpt" on a floppy -- along with a hand written cp/mkdir
all-in-one binary because, when you use the "Fixit" option it does not
chroot you to the fixit floppy, meaning you'll need /libexec/ld-elf.so.1
and /lib/libc.so.5, because for some reason critical system utilities are
built dynamically now.... but I am straying from the topic -- and ran "gpt
migrate" as recommended in its man page. Now gpt no longer recognizes the
the disk at all. gpt show fails entirely. gpt -vvv show lists some
entries, but the sizes are all very wrong, as if they were truncated.

Anyone know the specific tricks involved in getting all 4TB used, even if
it has to be in 4 different slices, or am I stuck with using just 2TB?
We're gonna have to go with Linux on this particular server since we need
it up today but we'll be getting another one soon and I can try things
there.