Upgrading to vSphere 5: Understanding the New Licensing Model and Its Impact on Your Environment

As many of you may already be aware, VMware has recently launched vSphere 5, the latest version of its virtualization platform. While this new release brings several exciting features, such as support for 32 vCPUs and 3D acceleration for Windows Aero, it also introduces a new licensing model that may cause some concerns for existing vSphere users. In this blog post, I will try to address some of these concerns and provide a better understanding of the new licensing model and its impact on your environment.

Firstly, let me clarify that the new licensing model is based on the concept of “vRam” or virtual RAM, which is calculated per cluster rather than per host as in previous versions. This means that you can now use up to 288GB of RAM for your virtual machines (VMs), compared to the previous limit of 96GB. However, this increase in available RAM does not necessarily translate into a corresponding increase in the number of VMs you can run, as you will still need to maintain a certain level of resource reservation for high availability (HA) purposes.

One of the main concerns that I have heard from existing vSphere users is that the new licensing model may lead to a situation where some RAM is left unused, resulting in a “wasted” investment in hardware and licenses. However, VMware has thoughtfully addressed this issue by introducing the concept of “overcommitment”. In essence, overcommitment allows you to allocate more vRAM to your VMs than the physical amount of RAM available on your hosts, knowing that some of the allocated vRAM will be unused due to the need for HA reserves.

To illustrate this point, let’s consider a scenario where you have three hosts with two CPUs each and 128GB of RAM each (for a total of 384GB). Under the previous licensing model, you would only be able to use up to 96GB of RAM for your VMs, leaving 288GB unused. However, under the new licensing model with overcommitment, you can allocate up to 288GB of vRAM to your VMs, knowing that some of this allocation will be unused due to HA reserves.

So, what does this mean for you as an existing vSphere user? Firstly, it means that you can now take advantage of the increased available RAM and run more demanding workloads without worrying about running out of RAM. Secondly, it means that you can still maintain a certain level of HA reserves without sacrificing too much performance or resource utilization. And lastly, it means that you can still use the same number of hosts as before, but with more flexible and efficient use of your hardware resources.

In conclusion, while the new licensing model in vSphere 5 may seem daunting at first, it is designed to provide more flexibility and efficiency in your virtualized environment. By understanding how overcommitment works and how to effectively allocate vRAM to your VMs, you can take full advantage of the new features and capabilities offered by vSphere 5 without worrying about wasted investments or reduced performance.