Blog post in two parts, a review of licensing in vSphere5 and then the point of the post regarding the mechanisms of adding additional licensing to a vSphere5 server.
The new licensing model with vSphere5 requires “stacking” of licenses to achieve vRAM allocation levels (or entitlements) above the 24/32/48GB per proc the licenses are now limited to.
So a single 2-CPU standalone server with two CPUs of vSphere Standard can have running VMs with up to 64GB of total vRAM configured. To allocate more than 64GB of vRAM to VMs an additional license needs to be purchased and allocated.
For servers managed by vCenter the vRAM entitlements for the servers are “pooled” – two servers each with two CPUs of Standard can run up to 128GB of VMs between the two of them. If you want to allocate additional vRAM to VMs in the pool, you add additional licenses. Those licenses will need to be allocated to one server before vCenter will add the additional vRAM entitlement to the pool.
Note that vRAM is pooled per license family – all Standard licenses are pooled and all Enterprise licenses are pooled. Interestingly enough you were prevented in 4.x’s EULA from managing different license levels from one vCenter server but the VMware presentations and documentation for vSphere5 make reference to license family pools on one vCenter server …
Now the interesting part.
The catch is, only one license string can be allocated to a server at a time.
Just like for 4.x there is a radio button for selecting the license associated with the . With 4.x if you upgraded a server from 2CPU to 4CPU you would need to call up VMware licensing (no way to do it online that I know of) and get the two 2-CPU strings combined into one.
The same process will need to be followed with vSphere5 when you add vRAM entitlements. This process should be fairly uncommon and painless since vSphere Linked Mode will pool licenses between all the licenses allocated to servers it manages, but if you are doing just-in-time-licensing (VMware requires the license to be purchased before the additional vRAM is allocated) you may be calling the licensing desk often.