I am running CentOS 5.9 i386 on a Citrix XenServer 5.6. I installed CentOS with 3GB memory, 2GB swap. I later wanted to add more memory, so I shutdown the server and configured the VM for 8GB. After rebooting, the server still shows available memory to be 3GB.
I tried editing /boot/grub/grub.conf and adding mem=xxM to the configuration, however the system still reports that I only have 3GB memory available.
Is there some configuration I am missing that is causing CentOS to miss the additional memory? Any help is much appreciated, and thanks in advance
EDIT: Below is the results of uname-a
[root@SERVER ~]# uname -a
Linux SERVER.DOMAIN.EXAMPLE 2.6.18-348.el5 #1 SMP Tue Jan 8 17:57:28 EST 2013 i686 i686 i386 GNU/Linux
Best Answer
As MadHatter has pointed out, you need to install the PAE kernel and change GRUB default settings to boot to this kernel. This is needed if you have more that 4GB memory installed.
Step 1: Install kernel-PAE
Step 2: Edit /etc/sysconfig/kernel
Step 3: Change GRUB to boot to kernel-PAE by default. Edit /etc/grub.conf and change the default number to match the boot order number for kernel-PAE. Boot order numbers start with 0.
For example, in/etc/grub.conf, my default below should be set to 1 in order to boot kernel-PAE