There are a few things to think about with regard to licensing  first, vSphere 4.1 now allows for DRS affinity so that VMs only move between certain hosts of a cluster.  I’m still waiting for a definite answer from my VMware friends but that should allow you to protect some VM’s and set their DRS Affinity to only the hosts that you own SRM CPUs for and still keep the full cluster for the unprotected VMs. Previously, VMware would recommend that you create a separate cluster for your “protected” VMs if they were a small subset of the whole.  Now with DRS Affinity, you can dictate that certain “protected” VMs only move between a subset of a cluster.  We’ll still have to wait and see the final ruling from VMware but I’m thinking that would work in the short-term for those in the per-CPU dilemma.

The second feature of the new licensing that I really like is the rolling average of VMs over the last twelve months.  What that translates to is that now I need to buy what my daily average of VMs protected would be over a 12 month period.  If I have certain points of the year where my VM count spikes, this average would be monitored by vCenter and alarm if I am going over my licensing limits.  However, I would only need the average number of protected VMs over the past year.  The system will continue to run after going over your limit but that’s definitely not something I would condone (Famous VMware SE saying: ethics don’t ship in the box people).

The per-vm licenses are sold in blocks of 25 and range from $1,250 to $11,250 depending on the product.  Per-vm licensing will be available for Chargeback, Appspeed, SRM, and, later this year, CapacityIQ.  You can find more information on VMware’s website here.

The last question I had was, “How do I know what my rolling average is for those licenses?”  The good news is that once you enter in a license key, the new license reporting manager in vSphere 4.1 will tell you what your rolling average is year-to-date.  Looks like someone was planning ahead.