Eye-popping load averages

[Joseph Formoso]

Folks,

	I've see something happen on our IMP box a few times now, and
was wondering if any of y'all have ever seen similar behavior.  First,
of course, the specifics:

Linux Mandrake 7.0
IMP 2.2.7-cvs
Horde 1.2.7-cvs
Apache 1.3.19 w/mod_ssl and PHP4.0.4pl1

	It talks to an IMAP server which lives on an IRIX box.  The
problem we've seen is that, occasionally, our IRIX box gets a load
average spike (often due to that wonder of SGI ingenuity, nsd).  The
spike causes our IMAP and POP servers to stop taking connections (by
design; we have some services suspend themselves when the load average
hits a certain point to try to throttle the out-of-control spin).  This
has happened a few times over the past few months, and each time, the
IMP box has had its load average to through the ceiling immediately
after the IRIX box's did, and could only be fixed by shutting down and
restarting Apache.  The correlation suggests that *something* in the
IMP/PHP/c-client/Apache setup is getting put in a strange state when
the IMAP server suddenly goes away (or possibly when it suddenly comes
back).

	Anyone else ever seen anything like this?  Failing that, any
suggestions for trying to find a root cause?  I'm assuming it's
something at the PHP/c-client level, but on the off chance that IMP is
in some way involved (I don't know how), I figured I'd ask.

	Thanks in advance for any suggestions.


					--Joe


-----
Joe Formoso (jformoso@stevens-tech.edu),
  Senior Systems Administrator, IT Department, Stevens Institute of Technology