SearchServerVirtualization.com: What are some corporate desktop usage trends that dovetail with the coming of desktop virtualization?
Douglas Strain: More companies support the mobile environment and have workers -- such as helpdesk reps -- working fulltime at home. This has forced companies to expand their management reach and maximize usage of Web-enabled applications and technologies. So, you already have a lot of workers outside the office accessing their corporate information and using
This trend will support an acceleration of thinner clients into corporate environments. They won't be as thin as typical thin clients, and that will make them more appealing to users. Some apps will reside on the client still, but not those business-sensitive ones.
We have seen [situations] where corporate lets the users customize virtualized desktops. They can get onto the device and see a picture of their kids, for example. I think there is value in that [for users], and it lowers [users'] resistance.
Why are IT organizations considering desktop virtualization?
Paul Miller: Virtualization brings cost points that make moving to a new desktop infrastructure attractive. When you can be running 60 to 100 clients on a single server blade, all of a sudden the cost equation looks great.
Price-performance looks good, too. It takes far less time to pull up email or an Internet browser on a virtual client than on a standalone laptop.
Douglas Strain: Corporate customers are trying to manage the cost of managing desktops in a large dispersed organization. Virtualization makes centralization of desktop applications possible, increasing manageability without [reducing functionality].
What's the security story for desktop virtualization?
Douglas Strain: Virtualization brings greater security. Companies are very concerned about laptop theft and employee or ex-employee hacking. Companies don't want sensitive data stored on a laptop or a home worker's desktop, so having a mission critical application back on the server, rather than residing on the PC, is appealing.
We have a customer, a school district in Florida, that has to manage desktops in schools around the county. There were big concerns about security issues around having all that data dispersed. They saw big savings in security spending [with client virtualization].
Does virtualization give longer life to existing desktops?
Paul Miller: The trend in the desktop world has seen an increase of 50% to 100% more memory with every follow-on generation of client deployments due to application or operating system needs. If you look at an old desktop, with a virtual client solution like virtual desktop infrastructure, you don't have to upgrade memory to run the new apps on the desktops. You can keep the existing desktop in place as a virtual client.
Douglas Strain: The Florida school district wanted to use virtualization to extend the life of the client devices that they already have, and they are doing that, using the devices they have.
Is it more common, though, for companies to bring in desktop virtualization when there's a big desktop upgrade?
Paul Miller: Looking at change processes in corporate IT, they are still purchasing silos. The one who does desktop purchases is different from the one who does server purchases. So, the change to virtualization often takes place when a desktop refresh is needed. In these cases, we help users dispose of those assets by reselling them or recycling the materials.
Changes coming in Microsoft Vista and Office 2007 will force corporations to either buy new desktops or find some other way to extend the lifecycle of desktops. Virtualization can help in either situation.
At this point, will virtualization work for untethered workers who use mission critical applications while not online?
Douglas Strain: This is not a solution for every environment. Sales tools may not be a good fit if the user of those tools is really untethered. You have to look at which apps you can centralize.
There is some uncharted territory, and we are going to have to learn along with our customers.
What are some of the challenges you've faced so far in desktop virtualization projects?
Douglas Strain: One challenge has to do with the fact that, in some environments, workers are not always at their desks. But you have to be ready for peak times when almost all are at their desktops.
Paul Miller: If, say, at the end of every quarter a CEO does a webcast report that everyone must access, that spike has to be planned for. Over your entire annual cycle, you have to determine what the events are that could drive the peaks and spikes of usage and how you will balance those systems 50% of the time.
Douglas Strain: In the more erratic logon environments, the customers have to step back and think about high spike times.
Circling back to the cost issue, how will desktop virtualization change licensing?
Douglas Strain: There are two levels of savings in a VDI environment regarding oversubscribing.
First of all, if an IT manager has to support, let's say, 1,000 desktop users, he/she would normally need to purchase 1,000 desktops, each with a Windows XP license and the associated productivity software. In addition, each of those 1,000 desktops would need sufficient memory and hard drive capacity to run [its] copy of Windows XP and productivity software.
In a VDI environment, that IT manager could assume that he could support those 1,000 users with less than 1,000 virtual machines (each with a license of Windows XP). That's because in a typical office environment, some fraction of those users is not using their desktop. Therefore, the IT manager may only need 800 to 900 virtual machines.
Secondly, one of the features of VMware ESX is its memory allocation scheme. A static memory page that is identical across two or more virtual machines only needs to be in memory once. If you take a server running 60 to 100 VDI sessions, each of them with Windows XP Pro and the same productivity applications, there is a substantial memory savings because many of those memory pages only have to be loaded once and used by many or all of the VDI sessions.