Freeze when running freebsd-update

[Dieter BSD]

Robert writes:
> 3) the box is responsive to hitting enter at the console (it produces
> another login: prompt)

Getty is in memory and can run.

> 5) if I try to login to the console, it lets me enter a username then
> locks up totally, it does not present me with a password: prompt.

Login(1) is not in memory, and the kernel cannot read it from disk
for some reason.

I can get this symptom by writing a large file to a disk on a
controller that FreeBSD doesn't support NCQ on. I assume there
is a logjam in the buffer cache. Something trivial like reading
login in from disk that would normally happen in well under a
second can take many minutes.

Perhaps geli is causing a similar logjam? Does it hang forever or
is it just obscenely slow? If it truely hangs forever it is
probably something else. Is there disk activity after it hangs?
Can you try it without geli? systat -vmstat might provide a clue.