topic Linux Memory Upgrade in Operating System - Linux

Linux Memory Upgrade

Duffs — Thu, 22 May 2008 09:23:38 GMT

Hi,

I am attempting to upgrade a redhat server running on a HP proliant BL25p from 4G to 10G but the OS does not pick up the new memory even though it gets detected at the BIOS on bootup.

I have done some research and discovered that certain OS's may not report all installed memory for HP ProLiant Servers with 4G or greater of memory if PAE mode is not enabled.

Can anybody tell me how I can enable this mode (PAE) or essentially how I can get the OS to pick up the additional memory?

The OS I am using is as following:

[root]# uname -a
Linux rhofa1 2.4.21-27.ELsmp #1 SMP Wed Dec 1 21:50:31 EST 2004 i686 athlon i386 GNU/Linux
[root]# cat /etc/issue
Red Hat Enterprise Linux AS release 3 (Taroon Update 4)
Kernel \r on an \m

Rgds,
D.

Re: Linux Memory Upgrade

Matti_Kurkela — Thu, 22 May 2008 12:24:03 GMT

Whoa, you have a RHEL 3 distribution, and it's not even up to date with patches (at Update level 4 instead of something like 9).

The first step would be to confirm your CPUs support PAE. That can be done by looking at the "flags" lines at /proc/cpuinfo. If "pae" is mentioned on those lines, you have PAE support in your hardware.

The second step would be the OS support. You would need a kernel that has CONFIG_HIGHMEM options set to support more than 4G of memory. If you're using kernels packaged by RedHat, you could check the kernel options by reading the /boot/config- file that matches your current kernel version.

The BL25p blade has Opteron CPUs, so I believe this RedHat Knowledge Base note is exactly what you'll need:
http://kbase.redhat.com/faq/FAQ_43_3551.shtm

MK

Re: Linux Memory Upgrade

Steven E. Protter — Thu, 22 May 2008 12:33:29 GMT

Shalom,

Try installing and booting off the hugemem kernel.

SEP