A little help please guys or a pointer in the right direction for a configuration/setup recommendation. Whilst I have been using the XEN hypervisor in our office/dev environments for some time, I am preparing to deploy the latest XCP/Xen build for our live/collocation installation. To date I haven''t used any virtualisation at all in our live environment. Our setup is relatively straightforward with a physical three tier model: . Presentation tier (web servers, smtp, etc.) . Logic tier (business and operational servers) . Data tier (database and storage) I am going to leave the Data tier non virtualised and virtualise (compress) the logic and presentation tier onto the same physical hardware. So the example scenario is: . Both the Presentation and Logic tiers currently have 6 physical servers each (12 total) in a load balanced (shared nothing) arrangement. These will be replaced with 3-4 physical servers running at least two VM''s on each. . How would you set up the XEN environment for dynamic workload structures? . If spikes come through via the presentation tier how do you prioritise CPU/bandwidth to these servers/VM''s? . Likewise if the presentation tier is acquiescent then how do you control it such that if the logic tier gets busy it can consume idle CPU/bandwidth? Regards, Chris