December 15,2010 marks the date of change with VMware's licensing - at least as it comes to Site Recovery Manager. VMware is shifting from a "per CPU" license model to a "per VM" license model on most management products. Why is VMware making the change?

According to VMware, " per VM licensing for management better matches how customers use the products, especially in the cloud." The revised license model provides the customer with the ability to protect what they want. The new licensing model also makes it "easier" where you don't need to understand what cores you have, or how many CPU licenses you have. If you look at the current per CPU model, which requires the user to license each CPU of the VMware ESX host being protected by Site Recovery Manager, every virtual machine is covered - even VM's that don't matter, like test machines. In a real disaster, very few people are concerned about making sure that their test VM's will power up at the DR site automatically. Under the new "per VM" license model only the critical virtual machines that need to be protected are licensed for coverage.

This new license change is important to understand, as it could require an increase in license cost for a protected VMware Site Recovery environment. As an example, a customer with 4 ESX hosts (each with 2 CPUs) running 100 VMs would require 8 x VMware SRM per-processor licenses at $1,750 (retail) each, for a total of $14,000. In comparison - the "per VM" license model would require a purchase of 4 x 25 VM license packs at $11,250 each, for a total of $45,000!

If you have Site Recovery Manager today - you're safe. You can keep the per CPU license model, but if you add any additional servers in the future to your SRM cluster, you will need to convert to a per VM license model. VMware is being pretty generous with their CPU license model - to - Per VM license model conversions at 5:1 (5 VM licenses per CPU license) but don't wait to convert. My recommendation is to buy the SRM per processor licenses you may need for the next 12 months and buy them before December 15.

Other VMware products that fall under this new licensing model include: CapacityIQ, AppSpeed and Chargeback.

As a reminder, Canvas Systems is a VMware partner, so if you are looking to buy these additional licenses, feel free to reach out to me directly at khouston AT canvassystems.com.

Kevin Houston is Vice President of Servers and Virtualization for Canvas Systems and also maintains BladesMadeSimple.com - a blog focused on all things related to blade servers.