we are running SL5.6 x86_64 (2.6.18-238.9.1) on a 96GB machine without
issues. 

does the bios report 48GB of ram when the OS sees 32? (we had an other
machine with bad ram/memcontroller that reported varying amounts of ram
after every reboot)
and how much ram is seen by dmidecode?

stijn

> 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).

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