I'm creating new virtual Linux servers on ESXi hosts. The existing systems are 32-bit RHEL with 4GB RAM. I am planning to create the new servers with 4GB RAM and run 32-bit CentOS 5.

If I want to add more RAM later I'd need to move to a PAE kernel. Is this possible / desirable ?

Thanks, Mark

Is the only changed needed to install a PAE kernel and boot from it? Does everything else stay the same?


Yes, as you say, just install the PAE-aware kernel and boot from it.

As a matter of fact, if you have 4GB of memory allocated to the VMs now, you might see an improvement with the new kernel. I'll bet that if you look right now on a non-PAE kernel'd host, you'll find you have about 3.3GB of available memory, not 4.0GB.

  • make sure /sys/sysconfig/kernel gets updated to PAE also. - had that bite me in the past. – Sirex Feb 27 '12 at 15:09

It's possible but I'd suggest you went with 64-bit now unless there's a good reason not to.

  • 1
    It's arguable wether it's a good reason but the existing machines are 32-bit, the database program is 32-bit and the jump from the existing systems to anything else will be big nevermind changing to 64-bit. – mmcg Dec 14 '09 at 16:19

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