[CentOS] ESXi, KVM or Xen?

Sat Jul 3 16:35:17 UTC 2010
Keith Beeby <k.beeby at albion.co.uk>


We went for Esxi, with Vmware essentials, cost about £300 for 3 hosts managed via vcenter, so far so good most vm's are CentOS 5.x

Running NFS shared storage on RHEL



On 3 Jul 2010, at 04:52, Emmanuel Noobadmin <centos.admin at gmail.com> wrote:

> Which of these would be the recommended virtualization platform for
> mainly CentOS guest on CentOS host for running a virtualized mail
> server? From what I've read, objectively it seems that VMWare's still
> the way to go although I would had like to go with Xen or KVM just as
> a matter of subjective preference.
> VMWare's offering seems to have the best support and tools, plus
> likely the most matured of the options. Also given their market
> dominance, unlikely to just up and die in the near future.
> Xen would had been a possible option except Redhat appears to be
> focusing on KVM as their virtualization platform of choice to compete
> with VMWare and Citrix. So maybe Xen support will be killed shortly.
> Plus the modified xen kernel apparently causes conflict with certain
> software, at least based on previous incidents where I'd been advised
> not to use the CentOS xen kernel if not using xen virtualization.
> KVM would be ideal since it's opensource and would be supported in
> CentOS as far as can be reasonably foreseen. However, looking at
> available resources, it seems to have these key disadvantages
> 1. Poorer performance under load.
> http://wiki.xensource.com/xenwiki/Open_Topics_For_Discussion?action=AttachFile&do=get&target=Quantitative+Comparison+of+Xen+and+KVM.pdf
> This 2008 XenSummit paper indicates that it dies on heavy network load
> as well as when there are more than a few VM doing heavy processing at
> the same time. But that's two years ago and they weren't using
> paravirtual drivers it seems.
> http://vmstudy.blogspot.com/2010/04/network-performance-test-xenkvm-vt-d.html
> This  blog testing out Xen/KVM pretty recently. While the loads are
> not as drastic and neither the difference, it still shows that KVM
> does lag behind by about 10%.
> This is a concern since I plan to put storage on the network and the
> most heavy load the client has is basically the email server due to
> the volume plus inline antivirus and anti-spam scanning to be done on
> those emails. Admittedly, they won't be seeing as much emails as say a
> webhost but most of their emails come with relatively large
> attachments.

> 2. Security
> Some sites point out that KVM VM runs in userspace as threads. So a
> compromised guest OS would then give intruder access to the system as
> well as other VMs.
> Should I really be concerned or are these worries only for extreme
> situations and that KVM is viable for normal production situations?
> Are there other things I should be aware of?
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