5.4-RC2 freezing - ATA related?

[Peter Jeremy]

On Mon, May 16, 2005 at 06:40:01AM -0600, Elliot Finley wrote:
>The system freezes, but isn't totally dead.  It'll still respond to pings,
>the screensaver still functions, but it won't respond to a CAD at the
>console.  But if I press 'Enter' at the console, it'll give me a 'login:'
>prompt, but after entering the username, it never comes back with the
>'password:' prompt.
...
>On my lightly loaded systems, it happens rarely.  On my mailserver (fairly
>heavy disk load), it happens quite frequently.

This could equally be a filesystem deadlock (race-to-root) rather than
something in the ATA controller.  Do you know if it happens gradually
(starts with one or two non-responsive, unkillable processes and gets
worse until nothing happens)?

>How can I troubleshoot this?

Re-compile the kernel with:
   options KDB
   options DDB
   makeoptions DEBUG=-g
and ensure you have a "dumpdev" in /etc/rc.conf.  When you get a
lockup, drop to DDB (Ctrl-Alt-ESC) and run "show lockedvnods", "ps"
and "call doadump()".  If you post the output (a serial console will
help here) someone might be able to provide more pointers.  (The
crashdump will help with later debugging).

Note: If you don't have another FreeBSD system handy, a hard copy
of ddb(4) will be very handy if you want to play around in DDB.

-- 
Peter