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Nonpersistent vs. persistent desktops: Why VDI should persist

Using persistent desktops for VDI makes application delivery more flexible; plus, they're similar to the physical desktops you already have.

Want your VDI project to be a success? Choose persistent desktops.

In the world of virtual desktop infrastructure, there are two basic kinds of desktops: persistent (also called personal or one-to-one) and nonpersistent (also called shared or many-to-one). Many VDI proponents claim that nonpersistent desktops are the way to go because they're easier to manage than persistent VDI. With nonpersistent, a single disk image is shared among many users. As each user logs in, he or she gets a clone of the shared master desktop, and then that clone is customized on demand with app virtualization (Microsoft App-V, VMware ThinApp, etc.) or with user environment virtualization (AppSense, RES, etc.).

While this seems like a great concept, the unfortunate reality is that it's impossible to virtualize every single app and user setting with these tools. For example, how do you handle new apps the user wants to install? They can't install to the master image since that's the image that's used for everyone, and they can't install into their own clone because the app would be lost when the admin refreshes the master image. (The ability to refresh a single master image is why you're using the nonpersistent desktop in the first place, right?)

Persistence comes naturally

In your existing pre-VDI environment, most desktops are persistent. Your users have laptops and desktops with hard drive images that persist between reboots. In most cases, users even have admin rights -- they can install their own software, and each image is different depending on the needs of the particular user. Sure, you might use some app and user virtualization (and you should), but any apps that can't be virtualized can be happily installed into a user's image manually.

More on persistent VDI

How persistent vs. nonpersistent desktops affect storage

Persistence affects VDI and Terminal Services security

One of the main reasons that VDI projects fail is because most pre-VDI environments are based on persistent images and most VDI environments are built around nonpersistent images. Companies spend too much engineering time trying to cram diverse images into a common one, and by the time they give up they've wasted several months and pissed off a bunch of VDI pilot users.

So when you move to VDI, don't try to re-engineer your desktops. If you've been using persistent desktops where users have their own admin rights, then keep doing it for VDI. (After all, if you want to move to a locked-down nonpersistent desktop image, you can do that with existing hardware.)

The reason you're not hearing this message much is because the storage technology needed to support VDI users and their personal images has just started coming out in the past year. (That's why many vendors always talked about nonpersistent -- that used to be all they supported.) But now that persistent images on VDI are possible, you can finally design a persistent VDI environment so that it mimics your physical environment. That's a sure-fire way to please your users and to create a successful project.

Let us know what you think. Write to us at moderninfrastructure@techtarget.com

This was last published in April 2013

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It depends on the use cases !
In education, call centers, for task workers, you will usually choose non-persistent desktops, because this is what you want. You can use personalized profiles (roaming profiles or similar) or even have no profiles at all.
For knowledge workers, persistent desktop is certainly better. But then, why bother with hosted VDI? There are very interesting alternatives such as VMWare/Wanova Mirage, Citrix VCI etc.
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If you let your users have admin rights on their computers, just stop reading. Do not look at VDi as a solution. You're already doomed and VDi will do nothing more than perpetuate this doom.

The writer of this article is clearly inexperienced in VDi deployments.

Persistent vs. non-persistent is a case by case decision. Look at a call center. Would you ever tell a call center NOT to use non-persistent desktops?

If you want to successfully deploy VDi, align your desktops with business goals. Desktops should be configured and setup to make the business successful.
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VDI solutions have come up keeping in mind COST, and then environment that is completely to partially controlled by administrators from IT department. If these two align to an organization's IT goals then VDI is an amazing thing. Persistent and Nonpersistent discussion is environment specific. I disagree to present a generalized opinion of "persistent VDI is the thing to go about". Having said that, persistent may help end users as 'transitioning' to non-persistent for later is the way to go in future.
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You can isolate the OS from the typical apps and the data the belongs to the user. If you give the user access to a shared drive and a method to add to "additional" software all you need is a script in place to connect the clone to the shared drive.
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