Kernel upgrade

Your yum.conf probably (and correctly) only allows yum to install a new kernel, not update it. You ought to be able to install a new one using:

yum install kernel

or

yum install kernel-smp

Depending on whether you have a multi-processor server. You should also check your /etc/yum.conf to see if you have kernel* in an exclude list.

 

I'm assuming that the latter, yum install kernel-smp, is for multi-processor servers?

I ask as my new CentOS 3.4 server's kernel is 2.4.21-27.0.2.EL, which seems a little old to me (perhaps I'm wrong, I often am) and so I'd like to upgrade the kernel before moving clients to the server.

On a related matter (and this is going so sound like a really silly question), how can I find out, through SSH, how many CPUs the server is running? This would let me know whether to use yum install kernel or yum install kernel-smp.

This silly question arises from the fact that this new server was supposed to contain a single cpu, however the Server Information in WHM lists 2 CPUs, and so I'd like some way to confirm this as being true. The odd thing is that the speed of both CPUs is listed as 2800.173 MHz - I'm wondering whether two CPUs really would have the exact same speed or whether the listing of two CPUs is due to some WHM or OS confusion. Any idea if the number of CPUs could be listed incorrectly?

 

2.4.21-27.0.2.EL is the latest RHE and therefore CentOS v3.4 kernel

You can tell if you have multiprocessors by looking at:

cat /proc/cpuinfo

It's most likely that you only have 1 CPU with Intel's HyperThreading (HT) enabled. It's no where near as fast as having 2 actual CPUs (you'd need a dual-core CPU for that) but it is usually quicker than a single one. All depends on what it is doing. A cpu with HT enabled should still use the SMP kernels (Symmetric MultiProcessing):
http://en.wikipedia.org/wiki/Symmetric_multiprocessing

The number of CPUs can be detected incorrectly, but only down, not up. Usually it's because the NOC has forgotten to enable HT in the BIOS.

 

Thanks again Chirpy! You actually beat me to it by a fraction of a second, as I was about to post a reply stating that I'd figured that bit out!

The CPU does have HT enabled, so that would explain the dual CPU impersonation.

As for the kernel, as long as its the latest that's fine!