Please tell me: What offers Persistent VDI over traditional desktops
- Published: Wednesday, 26 February 2014
Currently many VDI implementations are based on the so called persistent VDI methodology. The user gets a (virtualized) desktop in the data center, which is installed and configured (mainly) via the traditional available deployment systems. When I’m talking and discussing about Persistent VDI’s my alter-ego is banging against the door again. In this opinion article I will describe my vision why my alter-ego is coming back when talking about Persistent VDI.
To be completely clear first start with describing what a persistent VDI is (in this article) and why this type of VDI is getting commodity. The Virtual Desktop Infrastructure is around for a while and although VDI is used for several type of infrastructures nowadays or people suggested another name for the topic I want to discuss today it’s still the most often used name. In this article a VDI stands for a client operating system (Windows XP, Windows 7 or Windows 8.x) that is running in the data center, most often as a virtualized machine on a hypervisor layer.
This type of VDI is available in two flavors: non-persistent/stateless and a persistent/stateful VDI. As the names already implies the difference is that changes made to systems are preserved or lost. A non-persistent machine returns to his original state when the user ends his session and can be assigned to another user, while a persistent VDI keeps his state and is assigned to one specific user.
In the beginning many project started with non-persistent VDI’s but currently I see and hear that most VDI projects are based on a persistent VDI. Suppliers like Citrix, Microsoft and VMware are bringing this message, but also lots of well-known independent persons have the same vision (for example see Brian Maddens article. In this article I will not debate between non-persistent and persistent VDI, because I think it’s right to see that a persistent VDI makes more sense that a non-persistent VDI (as in 99% of the case, this can also be accomplished with a Server Based Computing solution based on a server operating system). I’m also not going to discuss the fact that for installing and configuration of the persistent VDI’s the already traditional deployment systems are used, again I agree with that also and it’s logical and would be not that clever to create a second deployment system for such machines.
However when talking about persistent VDI, as already stated in the introduction, my alter-ego Mr FatClient comes alive again.
Some years ago I already wrote a more generic opinion article about the fact that a Fat Client is not that bad at all and called it PDI (Physical Desktop Infrastructure). I still think that the vision in that article still applies to current infrastructures and that you can deliver the same or even better experience with a Fat Client in the 2.0 edition as explained in the Physical Desktop Infrastructure.
So tell me what offers a persistent VDI over traditional desktops
To start I will discuss reasons I have heard to use a persistent VDI, followed by arguments that I don’t think that are (fully) valid arguments.
Actually I hope I don’t have to argue about this argument anymore. When VDI was just launched it was indeed marketed as a cheaper alternative for the traditional desktop. Currently it is accepted that you don’t do a VDI implementation because it’s cheaper. Besides additional license, you need additional hardware (at least physical servers, but often additional storage, an storage accelerator and so on), while you still need an end-device (when not using the BYOD concept) to connect to the environment. Also with using persistent desktops the administration tasks are exactly the same, so there is also no reduction on maintenance level.
There are several persons already published articles on the internet, which describes this topic into detail like Harry Labana, Art Wittmann and Tom Pisello. So summarized VDI is definitely not cheaper than using traditional desktops.
The second most used argument is that VDI is more secure than using traditional desktops. Again also several articles are published about this topic, a good article series is by Shawn Bass. In the series Shawn explains into detail why VDI is not more secure and I totally agree on his vision about this topic. Especially with persistent VDI the situation is not different than with a traditional desktop expect that the machine is physically stolen, but it’s not about the device but about the data.
So running VDI for more security is also not a good argument to choose VDI over a traditional desktop.
I don’t know if this concept is around everywhere, but in the Netherlands it’s still a hot topic. Implementing flexible workplaces causes that less physical workplaces are required and the office building can be reduced or not extended (in case the company still grows). With using a VDI it does not matter where the user sits in the building. In theory this is definitely true, however in practice users are always picking the same spot every day, the user is not as flexible as expected. Secondly flexible workplaces can also be created by using traditional desktops combined with a clever application deployment system preferable using application virtualization. With limited efforts a traditional desktop can be as flexible as a flexible workplace via VDI. Don’t forget that in most organizations the majority can execute their daily tasks with just a few applications. It’s the majority that requires specific difficult applications and that kind of people often don’t have a flexible workplace concept in use.
In my Back to the future: PDI article I stated this as one of the challenges using a traditional desktop where you required a SBC or VDI infrastructure to fulfill this need. In that time frame it was not easy to configure an enterprise ready remote access solution using traditional desktops. However the game has changed nowadays by Citrix adding the RemotePC feature into XenDesktop. It requires some additional (virtual) servers and of course additional licenses (XenDesktop), but not the physical servers and storage requirements of a standard VDI implementations.
RemotePC is actually working (check for example the article of Andrew Morgan) fine and can be definitely be used in enterprise solutions. So Citrix solved on of my latest challenges in my PDI concept.
BYOD is a difficult one. It’s still used in lots of discussions as the reason to use a VDI. Although I believe BYOD will become an important way to do business related tasks I don’t think that will require a VDI to do those tasks. As I stated in the option article Bring your Own Device: Hype or Reality for now it’s an additional way to connect the organization and only when real BYOD applications are in place it can replace the desktop model we still are using today. So probably the BYOD user also has another more traditional device to execute their daily tasks. Also there are developments on the client virtualization platform. It looks like the level 2 hypervisor is making a comeback with an upcoming release of the DesktopPlayer for Mac by Citrix and the Hyper-V implementation in Windows 8.x. In my opinion this is a good alternative to provide access to the infrastructure for temporary employees.
Don’t be shocked, but branch offices can be a valid reason to use VDI. In the Back to future PDI article is also mentioned Branch Offices with small bandwidth as one of the challenges. Actually this situation is not changed a lot in the timeframe. WAN lines are still getting a cheaper and there are possibilities using the internet as a tunnel, however there are still lots of locations where bandwidth is limited. For branch offices VDI can be a good alternative, however you also should consider accelerators/caching devices for a better performance. When there are limited branch offices (with small bandwidth connections) VDI still be pretty expensive for such scenarios. Also a Server Based Computing solution can be a better alternative as mostly branch offices don’t require specific difficult applications.
As the article subject is stating please tell me what offers a persistent VDI desktop over traditional desktops. Besides the branch offices scenarios I could not think of any valid reasons. However if you have one, please let me know via the comments option of the website and let’s discuss about is.