Until the release of Horizon 6 in mid-2014, per-user capital costs of virtual desktops (VDI) were typically higher than those of comparable physical desktops. The delta had been gradually eroded by a range of initiatives and was in many cases near-zero, but few organizations were able to achieve immediate capital cost savings by moving to VDI. The most significant factor in this was the cost of storage.
The release of VMware Horizon 6 changed this through the inclusion of Virtual SAN. Virtual SAN uses direct attached storage in industry-standard servers to build a virtual storage area network and to deliver a step-function reduction in unit storage costs: in a recent white paper, we evaluated three different deployment scenarios and highlighted capital savings of between 58 and 77 percent.
These savings are game changing (and market changing) as they shift the capital cost equation in favor of VDI. With Horizon 6, the virtual desktop is now a lower cost option than a physical desktop in both capital and operational terms (few commentators would argue that VDI wasn’t already ahead in operational cost terms, but that’s another story).
Show Me The Money
By now you might be saying ‘oh yes, show me’. That’s fair – so here’s our fact base and calculations.
Our starting point is VMware business case data, drawn from over 700 business cases created for customers using their own cost data. This data shows that with a typical network storage solution (for example, a hybrid appliance) VDI storage costs around $5 per GB today. The same data shows that VDI images also typically range from 30-80GB in size, depending on the specific user requirements. Even with higher numbers of users (and the associated rates of discount) the capital costs soon add up.
To balance performance and cost, Virtual SAN can use a combination of solid state and rotating disks to deliver the same (and often better) I/O performance at much lower cost than typical hybrid appliances. There are some additional considerations when deploying a hybrid Virtual SAN: every host server must be fitted with disks of each type and there must always be more than one of each disk type fitted in each server (for failsafe), but even with the slight over-provisioning of capacity this implies, the savings are real.
We drew our costs for various drives from public websites in June 2015. Since there was no change assumed in user profile, we assumed equal density of users per server and so all other infrastructure costs (servers, network switches, etc.) are neutral to the comparison. Here’s what we found:
- Scenario 1 – 5,000 task workers with a 30GB, non-persistent image
- Cost with a shared storage array – $37/user
- Cost with Virtual SAN – $15/user
- Scenario 2 – 3,000 knowledge workers with a 50GB, persistent image
- Cost with a shared storage array – $260/user
- Cost with Virtual SAN – $60/user
- Scenario 3 – 1,000 task workers with an 80GB, persistent image
- Cost with a shared storage array – $429/user
- Cost with Virtual SAN – $119/user
Full details are given in the VMware Virtual SAN and VMware Horizon 6: Cost Leadership Through Storage Savings white paper.
But What About Other Factors and Discounts?
Some of you may still be sceptical. Mileage may vary, it’s true and all of the above calculations were built using list prices, but we’ve reasoned that discounts would be applied similarly to whatever you buy – in other words, the numbers might change, but the percentage differences would not be affected. Why did we not factor in discount? Well, that might depend on a whole number of things, many of which are completely unrelated to VDI, or indeed storage.
OK, So What Next?
First, we suggest you find out more – that’s why we wrote up the paper and provided many more details. We know that no organization really wants to know average costs, they want to know their costs, which is why we’ve built multiple scenarios – we hope these will offer a framework to help you calculate how the costs might stack up for you. You might also want to visit our ROI Calculator, where you can build Virtual SAN into a much more detailed business case estimate.
But whatever you do, we believe that any organization considering VDI should now look at Virtual SAN. Why would you choose another solution that’s up to 300% more expensive?
Additional business and technical papers on Horizon and Virtual SAN are available on the Resource tab of this blog by searching for VDI.
