Wednesday 13 July 2011

VMware announce vSphere 5 and why all we're talking about is licensing

Yesterday, VMware announced the latest version of their flagship product: vSphere 5. This new version further extends VMware's lead over its competitors in the virtualisation space giving users the ability to run more and bigger VMs. Compare the capabilities of vSphere vs XenServer or Hyper-V and the ongoing  technical superiority of vSphere is apparent.

The new version offers new features such as the ability to automatically provision ESXi servers, storage enhancements (improvements to VMFS, Storage DRS and Profile-Driven Storage), a rewritten HA component, a Virtual Storage Appliance (which looks interesting for SMBs) and a new ESXi firewall. All of which are useful additions to the product.

Regular Enterprise customers have less to get excited about since the Auto Deploy, Storage DRS and Profile-Driven Storage features join the Distributed vSwitch, Storage- and Network-I/O control and Host Profiles as Plus-only features.

You would imagine that the conversations on Twitter and in blogs would be about these amazing new features. You would be wrong.

In releasing vSphere 5, VMware have made a significant licensing change. Whereas previous versions were licensed per CPU, with a limit on the number of cores per CPU, the new version is licensed per CPU with no restriction on cores. However, the amount of memory that vSphere can use is now licensed which VMware are calling the "vRAM Entitlement". The vRAM entitlement is the amount of RAM used by VMs.

A single CPU licence for vSphere 5 Enterprise comes with a vRAM entitlement of 32GB RAM. In a dual CPU ESXi host, this means the sum of RAM allocated to VMs is 64GB. In real terms, this would be equivalent to 32x2GB RAM VMs or 16x4GB RAM VMs.

The vRAM calculation is based on a pool of all resources, so in a cluster with 8 hosts, each with 2 CPUs and 32GB RAM, the total vRAM licensed is 512GB (8 x 2 x 32). 

While the VMware Licensing, Pricing and Packaging PDF tries to make it sound like good news for end users because we will no longer be limited to a number of CPU cores, I wonder how many users are CPU-bound. Looking at the infrastructures that I support, CPU utilisation is never the bottleneck; available RAM is.

The way around this limitation is to purchase additional CPU licences. So, if you have a server with 2 CPUs and 128GB RAM running Enterprise, the 2 CPU licences you have will only support 64GB vRAM, so you'll need to purchase another 2 CPU licences. Ker-ching for VMware!

I have some sympathy for users who have deployed large scale servers such as Cisco UCS blades. With a comparatively "normal" CPU count, but huge memory capacity, the licensing requirement for these environments has just gone through the roof.

One of the advantages of VMware vs its competitors is the number of VMs that can be supported on a single host. With Transparent Page Sharing (TPS) and memory compression, vSphere can typically run more VMs than XenServer or Hyper-V and overcommit allows a 32GB server to run more than 32GBs worth of VMs. Now, the savings made in terms of required hardware is offset by the need to purchase more licences.

For those of us with home labs that we use for testing, the vRAM entitlement may be a significant bottleneck. The HP ML110 G6 is a cheap, single-socket server capable of holding 16GB RAM. The free VMware vSphere Hypervisor (AKA ESXi) will only support 8GB per CPU. Whether a second free licence can be applied is unknown, but if not, many home labs will be limited to 8GB vRAM per host. This means more servers will be required which can cause significant spouse issues.

The VMware perspective is understandable. The ability for servers to run with huge amounts of RAM means that organisations require fewer servers, which means less money to VMware.

So is there any good news in this? The one thing that I can think of is it now makes charge back of VM resources easier to calculate. It appears that instead of managing "traditional" virtual infrastructures, where IT is a cost centre, VMware are shifting to a world where everything is provisioned through a cloud infrastructure and IT is a service. In this new world, the ability to charge back will be a core component.

In summary, some users will be unaffected by this change, some will need to pay a bit more to make full use of their environment, and others will need to pay a lot more. I'm sure that VMware's competitors will have a field day with this.

(All the above is based on the VMware pricing document (linked above). If anyone spots anything incorrect, please comment and I'll fix it. Thanks!).

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