Virtualization Oversubscription - What’s so scary? VMware CPU and Memory Maximums (5 of 20)

CPU and Memory are the main items people consider for Virtualized systems, so let’s lay down the maximums.

•        Virtual Machine Maximum

–       128 vCPUs per VM

•        Host CPU maximums

–       Logical CPUs per host 480 (Logical CPUs being simultaneous threads so that might be 240 hyper-threaded cores.)

–       Virtual machines per host 1024

–       Virtual CPUs per host 4096

–       Virtual CPUs per core 32

•        Maximum with a caveat: The achievable number of vCPUs per core depends on the workload and specifics of the hardware. For more information, see the link below for the latest version of Performance Best Practices for VMware vSphere

https://www.vmware.com/pdf/vsphere6/r60/vsphere-60-configuration-maximums.pdf

This raises 2 points.

·        Clearly it’s ok to oversubscribe CPUs 

·        There is no set number to tell you how much oversubscription is OK.

Memory VMware Maximums

Memory is a lot simpler.

•        6TB per Host

–       Well 12TB on specific hardware

•        4TB per VM

Having set out those few ground rules we can now look at memory oversubscription and I'll be doing just that on Monday.

There are still a few places left on our VMware vSphere Capacity & Performance Essentials online workshop so don't forget to book your place.

http://www.metron-athene.com/services/online-workshops/capacity-management-workshops.html

Phil Bell

Consultant