call boot(0) from DDB to avoid filesystem corruption

[cronfy]

Hello!

I am trying to find a way to avoid filesystem corruption after system
crashes. I am using FreeBSD 7.3 with DDB enabled. Sometimes system freezes
and only DDB (via CTRL-ALT-ESC) is available.

Documentation says there is 'call boot(0)' function that performs graceful
shutdown from DDB. To test it, I set up fresh install of FreeBSD 7.3 on a
new server. Then I started background 'tar -zxf ports.tar.gz' on all
partitions: /home, /usr, /var, /tmp and finally /. Waited ~30 seconds and
pressed CTRL-ALT-ESC -> call boot(0) -> Enter.

Unfortunately, DDB freezed on syncing bufdaemon. I had been waiting for ~5
minutes, but system freezed completely: I could not drop to DDB anymore and
keyboard was not working. I had to restart by reset.

What can be the reason of this last system freeze? I am using Adaptec
controller 3405 with FreeBSD's driver, can it be the cause? I do not know
indeed how to ask a good question about this situation because I have no
more ideas. Any help would be appreciated!

-- 
cronfy