[CentOS] Two cleanly installed CentOS 5.6 servers but with different Xen kernel versions

Fri Apr 15 14:18:04 UTC 2011
Hans Vos <hans at laissezfaire.nl>

Hello,

Earlier this week I installed a test server with CentOS 5.6 with 
Virtualization enabled during the installer. Today I installed another 
server using the same method (they are identical servers). I just did a 
yum update and I found something curious. Both servers have a different 
kernel. Server 1 is at 9.1 version and server 2 at 5.1. How can this be? 
How to I get the latest version on server 2? If I run yum update there 
are none available.

If I input xm info I get this one server 1:

host                   : server1
release                : 2.6.18-238.9.1.el5xen
version                : #1 SMP Tue Apr 12 18:53:56 EDT 2011
machine                : x86_64
nr_cpus                : 4
nr_nodes               : 1
sockets_per_node       : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 2400
hw_caps                : 
bfebfbff:20100800:00000000:00000940:0000e3bd:00000000:00000001
total_memory           : 4095
free_memory            : 383
node_to_cpu            : node0:0-3
xen_major              : 3
xen_minor              : 1
xen_extra              : .2-238.9.1.el5
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20080704 (Red Hat 4.1.2-50)
cc_compile_by          : mockbuild
cc_compile_domain      : centos.org
cc_compile_date        : Tue Apr 12 18:01:03 EDT 2011
xend_config_format     : 2

And on server 2 it is this:

host                   : server2
release                : 2.6.18-238.5.1.el5xen
version                : #1 SMP Fri Apr 1 19:35:13 EDT 2011
machine                : x86_64
nr_cpus                : 4
nr_nodes               : 1
sockets_per_node       : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 2400
hw_caps                : 
bfebfbff:20100800:00000000:00000940:0000e3bd:00000000:00000001
total_memory           : 4095
free_memory            : 383
node_to_cpu            : node0:0-3
xen_major              : 3
xen_minor              : 1
xen_extra              : .2-238.5.1.el5
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20080704 (Red Hat 4.1.2-50)
cc_compile_by          : mockbuild
cc_compile_domain      : centos.org
cc_compile_date        : Fri Apr  1 18:30:53 EDT 2011
xend_config_format     : 2

-- 
Met vriendelijke groet / With kind regards,

Hans Vos