[CentOS] Virtualization

Wed Jun 17 13:52:33 UTC 2015
Lamar Owen <lowen at pari.edu>

On 06/17/2015 03:28 AM, Mihamina Rakotomandimby wrote:
> MMmmm, I really thought ESX was in some way a RHEL derivative but when 
> reading 
> http://www.v-front.de/2013/08/a-myth-busted-and-faq-esxi-is-not-based.html 
> it is clearly not...
Older ESX had an RHEL 3-based service console; ESXi does not. Logged in 
to one of my ancient ESX 3.5 hosts:
[root at esx1 root]# vmware -v
VMware ESX Server 3.5.0 build-604481
[root at esx1 root]# cat /etc/redhat-release
Red Hat Enterprise Linux ES release 3 (Taroon)
[root at esx1 root]#

The relationship of the service console to the vmkernel is somewhat 
similar to the relationship of the DomO to the Xen hypervisor, or DOS 
and old NetWare 3; the vmkernel itself, along with all of its loadable 
modules, is not in any way shape or form 'based' on RHEL; RHEL is just 
used to manage the vmkernel system as a 'service console.'  This is much 
like how that Windows 386 (including 3.x, 95/98/ME) was not based on DOS 
(read 'Unauthorized Windows 95' by Andrew Schulman to verify) but uses 
DOS services in a warped fashion (Windows calls a DOS INT which is 
hooked by an illegal instruction 'thunk' back to the 386 mode VMMkernel 
which is the actual Windows Operating System kernel......).

With ESXi, VMware wrote their own CLI service console, and did away with 
RHEL as the service console.

But to address the direct question of the OP, I use KVM for many things, 
but I have older hardware in quantity on which I'll likely run 
Xen4CentOS with paravirtualized guests, since the processors in these 
blades do not have hardware virtualization extensions (early Opteron, 
but still very serviceable for what we want to do).  Too many LS20 
blades (about 200) to upgrade them all right now without either 
donations or other funding (but if anyone wanted to donate some IBM 
BladeServer HS21's or newer I would not turn down the donation, and we 
are a 501(c)(3)...... :-) ).