FreeBSD 6.1 Instability

Charles Ulrich charles at
Fri Oct 6 06:14:49 PDT 2006


We have been running FreeBSD on our mail servers for about as long as I can 
remember. Recently, we decided to go SMP to handle increased mail load. After 
assembling the hardware, installing the OS and software, and restoring all of 
our data, we noticed in testing that our first machine began hanging 
semi-regularly when it began processing lots of mail. Disabling SMP 
eliminated the hangs completely. We tried it all again on completely 
different hardware with exactly the same result. Our conclusion: somethings's 
buggy in SMP.

Here are the symptoms. The machine hangs, and becomes completely 
unresponsive.  It looks like a deadlock.  It will sometimes respond to the 
power button and shut down (without being able to first sync and unmount 
filesystems), and sometimes the power button event gets caught in the 
deadlock.  Sinceit's not actually a crash, there is no core dump or other 
debugging information. In the most recent situation, it hung at different 
points every time I tried to compile ezm3, after successfully compiling other 

We're system administrators, not kernel hackers, so this is a plea for help. I 
wouldn't know where to start, but I'm hoping someone can point me in the 
right direction. We're also willing to give a (trustworthy) FreeBSD developer 
root access to the test machine since it's just sitting idle right now. If 
you need to crash it, that's fine. We'll have people during normal business 
hours who know how to push a reset button.

Thanks for your time.
Charles Ulrich
Ideal Solution, LLC --

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