VDI Performance and Cost: A Deeper Dive

The third concern, also legitimate, is how we simulated a 200-plus desktop workload. You don't want to create an environment that purposely makes the storage solution look good, which means the simulation software is critical. It has to be able to recreate a real-world, highly randomized work day. The testing tool we used for this report is called Login VSI. The tool seems to be an increasingly popular choice for testing VDI storage, based on what we've seen at Storage Switzerland. Although I haven't researched it exhaustively, I've seen several published tests that used Login VSI, know of several others in the works, and am not aware of any complaints about its ability to simulate a real-world VDI environment.

This simulation software, made by a company called Login VSI B.V., puts a simultaneous number of virtual desktop instances through the steps of doing things a typical user would do, including receiving, creating and sending emails; manipulating Word, Powerpoint and Excel documents; and creating Zip files. These are all done randomly at different times by each desktop, creating what would seem to be a worst-case scenario for the storage system.

Another concern that comes up in tests like ours is disclosure. As regular readers of my column and the Storage Switzerland website know, we are often paid by storage vendors to create various forms of content. Velobit, the sponsor of the VDI lab report, and many other companies in the storage industry, are clients. LoginVSI B.V. is not a client of Storage Switzerland but it might be in the future. Without exception, all of those relationships have been accurately and repeatedly disclosed. Further, we accept no compensation from vendors based on the sale of products or on the success of their companies.

As do most analysts, we accept compensation for the papers and lab reports we write. This was the case with VeloBit and it was properly disclosed. I believe that this allows us to provide an educational service to our readers in a balanced, reliable way. We've never received a complaint from a user on the reliability or accuracy of our reports or our level of disclosure.

The VeloBit caching software we tested is one of a new breed of caching software products that use DRAM combined with software intelligence to oversubscribe memory for the purpose of delivering better performance than the classic 4-GB-per-desktop model. Our tests were an attempt to verify Velobit's particular product claims. In addition, we've spent countless hours researching the VDI storage market and will continue to do so. It's up to the reader to determine if this technology is worth consideration in their own VDI project.

We believe our lab report has value in two areas. First, it points out an important new tool that both storage manufacturers and customers can use to test VDI scalability. But its primary value is that it introduces a new concept to solving the storage I/O problem. This concept should significantly reduce the storage cost of a VDI project -- making CapEx savings a potential factor along with operational savings.