Virtualisation administrators planning a virtual desktop infrastructure (VDI) project have to stop thinking only about vendors, technologies and costs. They also have to stop thinking about VDI through the lens of server virtualisation. VDI is just plain different from server virtualisation.
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Here are the top five things to think about when planning a virtual desktop infrastructure project.
1. Storage, Storage, Storage!
Storage is the biggest killer of any growing VDI solution. In a VDI project, IT addresses the space considerations by either streaming the operating system (OS) to the virtual machine (VM), as is the case with Citrix XenDesktop, or by massively reducing the disk space required to create a desktop pool, as is the case with VMware View’s “Linked Clones”. However, neither approach deals with the IOPS generated by a virtual desktop once it is in use.
It is a misconception among many server virtualisation admins that “silly little desktops” do fewer workloads compared to a big, powerful, important server. It’s true that desktop consolidation generates different workloads compared to classical server consolidation, but once you get out of the proof-of-concept phase or beyond a simple deployment, a virtual desktop infrastructure does not scale on spindles alone. It almost always means that admins will have to resort to using cache or SSD to absorb the IOPS generated. This generally shows itself during logins, logoffs and redeployments of the desktop when IT wants to push out a new build.
2. Know your users; know their apps
This is where server consolidation admins often go wrong. Let’s face it, the reason most folks leave IT help desk and desktop support jobs is that in the snooty world of IT, these roles are looked down upon as low-skilled, low-paid and not challenging enough.
Many IT professionals seek roles on the server side in a bid to be as far removed from end users as possible. And that’s the trouble with this trend; once you start locking yourself in the server room, you are far removed from the mind-sets and priorities of the end users. Keeping aside the cultural barriers, IT admins often don’t fully know which applications are installed where, or how heavily used they are. This results in multiple versions of the same application on multiple devices.
Admins can use their virtual desktop infrastructure project as an opportunity to do some spring cleaning of business applications -- as long as they are prepared to conduct a proper audit. Admins could also use desktop analysis tools such as UK-based Centrix Software’s WorkSpace Discovery. Such tools do to a virtual desktop infrastructure project what capacity planning tools do to a server consolidation project.
3. Do not P2V your corporate image
All too often server virtualisation admins apply the same logic to desktops as they did to servers.
Frequently, they think that physical to virtual (P2V) is the quickest way to virtualise an existing environment. P2V is great for that old Windows NT4 box running an application no one knows anything about, but it’s not great for the line-of-business applications that could be installed to a clean virtual machine (VM) by simply importing across the data.
The same is true when it comes to virtual desktop builds. Physical desktops and virtual desktops are entirely different beasts. Check this out:
Physical desktops require vendor-specific drivers for devices. Virtual desktops do not.
- Physical desktops have a dedicated spindle for their IOPS. Virtual desktops do not.
- Physical desktops have loads of pointless graphically intense features switched on (such as Aeroglass, smooth scrolling, background wallpaper). Virtual desktops do not.
- Physical desktops have all the software they need installed to disk. Virtual desktops should not.
4. Adopt an application-virtualisation-first policy
Application virtualisation is a process by which you capture the installation of some popular software your users need and abstract it from the underlying OS so it runs its own “bubble” or runtime.
Popular tools for doing this include InstallFree, VMware ThinApp, Spoon and Microsoft App-V. Application virtualisation makes your applications easier to deploy and update, once they are separated from the underlying virtual desktop operating system. You can deploy the applications in the same way to any physical desktop, virtual desktop or shared desktop (Microsoft RDS, Citrix XenApp, 2x) environment.
I recommend adopting an application-virtualisation-first policy, just as we did with server virtualisation. When a new Windows application lands in your lap, ask if it could be virtualised. Hopefully this won’t happen too often, because applications generally work in a Web browser or across a multiple-platform environment such as a PC, Mac, iPhone, iPad, Android, Blackberry.
One word of caution: Not all apps are good candidates for application virtualisation. Some require device drivers in kernel mode to work. Just like server virtualisation, some applications have to be installed to the virtual desktop. But your goal must be to get the application virtualisation ratio as high as you possibly can.
By strategically adopting application virtualisation, you can easily port legacy applications from the PC-era into the new era, leaving the bloated and overstuffed traditional desktop layer behind.
5. Divide up the layers of your VDI cake
Desktops are divided into three main layers: the OS, applications and persona. In a good virtual desktop infrastructure environment, users shouldn’t care what the OS is, because their focus is on the applications.
The persona layer represents a new type of virtualisation -- virtualisation of your end users. Persona management means separating all the things that make the user unique -- the home directory, application settings and favourites from the OS and applications. This means, admins could get rid of the OS and the current application sets and re-deploy them without the user losing any data or metadata that matters to them.
VMware’s streaming user-profile technology, Persona Management, is only a fancier name for something admins already know about. In essence, it is a glorified “user profile” system that intends to merely improve rather than usurp Microsoft’s Roaming User Profiles.
Just like with applications, administrators must redirect the user settings out of the operating system and into different containers. They can do this with Microsoft’s Group Policy Object Folder Redirection and Roaming User Profiles. However, much of that technology hasn’t changed since Windows 2003. Instead, admins should consider a new breed of technology providers that stream a profile on demand and offer an entirely new way to encapsulate users’ persona.
Follow these five precepts and you should be well on your way to delivering a workable VDI project. Deviate from these and you will end up with a millstone, not a stepping stone, on your road to an application-delivery process.
Mike Laverick is a former VMware instructor with 17 years of experience in technologies such as Novell, Windows, Citrix and VMware. Since 2003, he has been involved with the VMware community. Laverick is a VMware forum moderator and member of the London VMware User Group. He is also the man behind the virtualisation website and blog RTFM Education, where he publishes free guides and utilities for VMware customers. Laverick received the VMware vExpert award in 2009, 2010 and 2011.
Since joining TechTarget as a contributor, Laverick has also found the time to run a weekly podcast called the Chinwag and the Vendorwag. He helped found the Irish and Scottish VMware user groups and now speaks regularly at larger regional events organised by the global VMware user group in North America, EMEA and APAC. Laverick published books on VMware Virtual Infrastructure 3, vSphere4, Site Recovery Manager and View.