FreeBSD 9 crash/deadlock when dump(8)ing file system with journaling enabled.

[Adam Strohl]

A few days ago I discovered that running dump(8) on a file system which 
has journaled soft updates enabled causes the machine to become 
unresponsive.  This is using FreeBSD 9.0-R.   I can still interact with 
the system a little bit (typing echos back) but never get a response to 
any action.   It seems like there is an I/O issue (deadlock or overload) 
and CPU usage spikes as well.  Resetting the machine seems to be the 
only solution once this occurs (CTRL-C, CTRL-ALT-DEL, logging in again, 
etc all fail).

Disclaimer: I have only tested this as a VM under ESXi 5.0 as I don't 
have access to any physical servers with 9.0 on them that I can test 
with (I will soon though).

As a side note this is the same issue reported here:
http://forums.freebsd.org/showthread.php?t=25787

For now I've turned off journaling (soft updates seem fine) and that 
works around the issue.

Let me know if I can provide more details etc!

-- 

Adam Strohl
A-Team Systems