How to increase RAM memory capacity in RHEL5 ?

[TwoProc]

I've never heard of such a limit at 24Gb, if you're seeing 24Gb, then you must be running either 64bit OS, or 32bit PAE OS, both of which can address more then 24Gb.

[Steven E. Protter]

Shalom,

There is no 24 GB limit in RHEL5. If you were using the 32 bit OS, the system would report only 4 GB of ram.

This system is running 64 bit OS as far as I can tell and is not reporting 8 GB of its memory.

You may have exceeded the servers hardware capacity or have bad memory in the system. You could also have hardware that requires memory go into paired slots and not be complying with hardware guidelines.

uname -a
# please post

SEP

[TwoProc]

I'm thinking that maybe it's time for a firmware update for that system. Motherboard, bios, etc. The only thing I can come up with is that there is a bug in the firmware layer.

One more thing to try, just for clarity - download one of the iso's for another Linux " live" variant: 64 bit Ubuntu, etc. I'm talking about one that will let you try the OS directly from the CD (or USB memory stick) without doing an install of OS. See what those report to you. If you try several 64bit OSs ( maybe RH, Ubuntu, Suse, Knoppix, Fedora) and they all come up with only 24Gb even though you can "see" 32Gb from the BIOS setup, then I'm betting firmware is an issue.

If other OS's see your ram fine, but not your installed one, it's time to look for a patch, open a call with Redhat support, or both.

[Viktor Balogh]

Hi Yaboto,

Are the newly installed DIMMs from the same vendor? And of the same size? Even though the BIOS sees the DIMMs and shows 32GBytes it might be that the newly added ones are not fully compatible with the old ones, because of interleaving. Check the manual for your hardware and look for the maximum supported RAM.

Regards,
Viktor

[Gerardo Arceri]

Also the "dmidecode" command can be useful to see if the system is seeing the additional memory, if you don't see it there then there is probably a problem with it.