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manouche 04-15-2008 08:26 PM

All RAM not being recognized on Linux RHEL after adding RAM
Okay, here are the specifics.

Linux version 2.6.18-53.1.14.el5 ( (gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)

The machine came with 2 GB RAM. I added 2 additional GB. When I rebooted, it only sees 2.59 GB

cat /proc/meminfo

MemTotal: 2590196 kB

So, looking around, I found information about modifying the kernel in grub.conf. So, here is what I have:

kernel /vmlinuz-2.6.18-8.1.10.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet

I modified it to be this:

kernel /vmlinuz-2.6.18-8.1.10.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet mem=4096M

After reboot, I still only see 2590196 kB

Somewhere on the web, it says that after reboot and after the GRUB boot screen has loaded, type e for edit and then choose the kernel line and add the mem=xxM or mem=4096M in this case. Eventually, it would boot.

I didn't perform this last step and am wondering if that is where it failed.

Thanks for any tips that you may have.

ranger_nemo 04-15-2008 09:27 PM

If you put the mem= in the actual grub.conf file, then you don't need to worry about editing the line as you are booting. You only need to do that if you want to temporarily boot with different parameters. Say you wanted to boot to the commandline once, and not into X, you would add " 3" to the end of the kernel line, hit enter to quit editing, then hit b to boot.

As for the memory problem, did you check to make sure the motherboard can handle four gigs of RAM? If it can, I would pull out the old RAM and just boot with the new, to make sure it's good.

manouche 04-16-2008 11:37 AM

unrecognized RAM
The motherboard support 32 G. It was intended to have Windows Server on it, but I installed RHEL. The vendor won't help because they only support Windows.

Anyway, I had thought about taking out the old ram and seeing what happens.

As I was reading on the web, I also found this:

Find out if the displayed quantity is the same as the known amount of RAM in your system. If they are not equal, add the following line to the /boot/grub/grub.conf or /etc/lilo.conf file, depending on the boot loader you installed:


So, the line would be:

kernel /vmlinuz-2.6.18-8.1.10.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet append="mem=4096M"

Is it true that 'append' can be used for lilo or grub?

jonesr 04-17-2008 03:59 PM

lilo uses a bare "kernel" line and passes kernel parameters via "append=".

grub expects the kernel parameters on the end of the "kernel" line, so you've already tried the "mem=" thing.

At startup, what do the BIOS configuration screens show for memory?

msound 04-18-2008 11:31 AM

How much ram does your system BIOS see? If the BIOS only sees the 2.59GB then you have a hardware issue and not an os issue. If BIOS shows 4GB RHEL only sees 2.59GB, then it would be a matter of figuring out whats wrong with your os config.


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