A few days back you mentioned:
> Upgrade your kernel to at least 2.6.12
> There's a known issue with earlier versions of the 2.6.x kernel and
> 64b CPUs like the Opteron. See kernel.org for details.
I did some searching and couldn't find any obvious mention of this issue
(I gave up after searching through the first few hundred instances of
"64" in the 2.6.12 changelog).
Would you mind being a little more specific about which issue you're
talking about? We're about to deploy some new 16GB RAM Opteron DB
servers and I'd like to check and make sure RH backported whatever the
fix was to their current RHEL4 kernel.