On Tue, Jan 5, 2010 at 6:32 PM, Alan Altmark <alan_altm...@us.ibm.com> wrote:
> It will be utilized even though you do not define three *virtual* CPUs. CP > will be able to run three virtual CPUs at once instead of only two. With > virtual 2-ways, you ensure that no single guest is using all three CPUs at > the same time. Unless the workload is suddenly increasing with 40% at the moment you go to the z10, you would look into *reducing* the number of virtual CPUs rather than increasing... "When you don't know, one will do. When you have measured, probably too." Only add virtual CPUs when all of the following apply: - when the application can exploit it - when there's advantage to get the work done faster - when the business justifies that application to consume a large part of the resources - when it is likely the resources are available when the application wants it - when you know someone who knows enough about the VM scheduler to do it right There's a cost to over-provisioning. Adding virtual CPUs to a virtual machine that does not need it will normally make it perform worse and will likely make the other virtual machines perform worse. And it makes it harder to get the resources to those who really need it. Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/
