Decisions, decisions: VDI storage considerations and choices
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After consulting and writing about desktop virtualisation for 17 years, since Citrix WinFrame, for the past eight of those years, I’ve been repeatedly answering the question, “Is this the year of VDI?”
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The answer this time, surprisingly, is quite possibly “yes!” But first a little background.
In 2012 I co-authored a book called The VDI Delusion. As you can guess from the title, I wasn’t exactly hot on VDI (virtual desktop infrastructure) at the time. The main problem back then was that VDI was being sold as a cheaper, more secure, and more manageable version of traditional Windows desktops. Unfortunately the lengths that customers had to go to in order to realise those benefits were extreme.
For example, people selling VDI claimed it was more manageable because multiple users could share a single desktop, via something called “desktop pooling” or “non-persistent images”.
The problem is that traditional Windows desktop and laptop environments don’t work this way, so if you want to convert from persistent traditional desktops to non-persistent VDI desktops, you have a lot of pain ahead of you. You have to try things like application virtualisation and user profile management and pool management and layering and all sorts of other things, all of which don’t work 100% and lead you to a failed environment that isn’t as flexible as what you had before VDI.
The same could be said about security. Sure, VDI desktops can theoretically be more secure than traditional desktops, but let’s face it - VDI is still about human users running Windows applications.
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Today’s security nightmares are not about stolen laptops - enterprise disk encryption software is a lot cheaper and easier to implement than VDI - rather, security folks worry about zero-day attacks and viruses and malware. Well guess what? That all exists in VDI too! Again, I’m not saying that you can’t make a VDI environment that’s more secure than a traditional environment - rather, I’m just saying that if you choose VDI, you don’t get a free pass at security.
These reasons, combined with the fact that designing VDI systems is enormously complex, are why VDI has only enjoyed a 1%-3% adoption rate so far.
But now that it’s 2014, what does the VDI market look like?
First of all, there were two major technological advancements, which came out in 2013, that are making VDI much more attractive in many scenarios.
The first is an advancement in storage technologies.
When VDI first came out, the reason everyone tried to use the non-persistent pooled desktop approach is because the performance needed to give every user his or her own unique desktop disk image was flat-out too expensive.
You would have had to spend £500 or more per user just on the storage, and that would have broken any cost model you had to justify VDI. But today’s storage vendors have technologies like in-line block-level single-instance storage - or “block-level deduplication” - that enable you to offer high-performance fully persistent disk images for somewhere in the neighborhood of £50 per user.
VDI is not a silver bullet, but you could be pleasantly surprised at what you find
This means you can design and manage your VDI desktops in the same way you’ve been designing your traditional desktops for the past two decades. In other words, you can design VDI in a way that actually works in your environment.
The other major improvement to VDI in 2013 was around graphics. Desktop computers and laptops have had graphical processor units (GPUs) for years. Everything a user does - from Alt-Tab’ing through applications to surfing the web to video chatting - requires a GPU. Unfortunately hypervisors such as VMware vSphere and Microsoft Hyper-V have not traditionally virtualised GPUs, so even if you had them installed in your VDI servers, your VDI desktops did not know they were there.
That changed in 2013. Led by Nvidia with its Grid technology, we now have full GPU support in VDI desktops with products like Citrix XenDesktop and VMware Horizon View when running on the latest hypervisors. This means VDI users can now do everything in their remote VDI desktops that they could do in their traditional desktops and laptops.
These two technological advances, combined with Moore’s Law continuously driving down the cost of server hardware, mean that VDI is an option for millions more users than it previously had been.
You can see proof of this every day. From 2006-2013, I could count the number of large (more than 10,000 seat) VDI deployments on one hand. But thanks to these improvements, I’ve seen more large VDI deployments in the past three months than in the past eight years combined.
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To be clear, this does not mean that VDI is right for everyone or that VDI is the sole future of the enterprise Windows desktop. It simply means that VDI is a viable option for more users than ever before.
So is VDI right for you? That depends. The most important thing to understand is that VDI is not an “all-or-nothing” play. VDI is nothing more than a form factor option. Some of your Windows desktops will run on desktop computers, some on laptops, and some on VDI. Each has its advantages and disadvantages.
VDI is not a silver bullet. No matter how good VDI gets, using a Microsoft Windows desktop interface that was designed for a large screen, a keyboard, and a mouse, will always be clunky from an iPad. But if you haven’t looked at VDI in a while, take a look again with the latest technologies—you could be pleasantly surprised at what you find.
Brian Madden is editor of BrianMadden.com and an internationally recognised expert on desktop virtualisation.
If you’re interesting in digging deeper into VDI, Brian is hosting a forthcoming conference called “BriForum” in London from 20-21 May, 2014. BriForum is a vendor-neutral, highly technical conference dedicated to end-user computing technologies like VDI. This is the event’s fourth year in London, and will be attended by hundreds of geeks who will share their stories and lessons learned with VDI projects.