On Thursday, June 09, 2011 07:22:56 PM you wrote:
> That's a significant chunk of RAM for such an old codebase. Is there
> any reason not to simply update to SL 6.0 and avoid the support
> problems?

What are you talking about, being large for an old codebase?  On x86_64 upstream has supported far more than 48GB since version 3 days (128GB to be exact, according to http://www.redhat.com/rhel/compare/ ).

While I don't have a machine with more than 32GB of RAM currently, I wouldn't have any problem using CentOS or SL 5.6 (or either SLC or SLF) on x86_64 with that much RAM.  The EL5.6 kernel isn't aged yet, not by a long shot.

SLC5 to SLC6 is not an update, it is a major upgrade.  There may be very significant reasons to not upgrade for the OP.

In any case, this doesn't answer the OP's question of why SLC5.6 doesn't see the same thing as upstream EL5.6 but being built from the same source.  I would ask the OP to see what both SL (non-C) and CentOS 5.6 say about the machine and see if either see things like SLC or like upstream.  It should be a pretty simple and quick test, especially if the OP uses the LiveCD to do it (which should work ok, assuming all the tools are there).