Persistent vs. Non-Persistent VDI
Virtual desktop technologies are changing the ways companies do business. Instead of having individual on-premises hardware workstations running their resident desktops, planners can use something called Virtual Desktop Infrastructure (VDI) to offer end users the same sort of environment — without the same hardware framework.
Within Virtual Desktop Infrastructure, there are two types of choices: persistent and non-persistent VDI. Each one has its own benefits and disadvantages in the corporate IT context.
What Are Persistent And Non-Persistent VDI?
Persistent VDI, also often called 'Stateful VDI', is a setup where each individual user’s desktop is uniquely customizable and ‘persists’ from one session to another. Customized data is saved in between user sessions and logons.
Non-persistent VDI or 'Stateless VDI,' on the other hand, doesn't save any of the shortcuts and file settings and other changes that an end user may make. In other words, it creates a kind of generic desktop that always reverts to the same original setup after a user logs out. Once the session is over, those things are gone unless you are using a product like AppSense or VMware UEM.
Pros And Cons Of Persistent Virtual Desktop Infrastructure
Think of persistent VDI as the “Cadillac Class” of VDI. It offers so much more functionality that some companies are apt to choose it as a default.
The primary benefit of persistent VDI, in comparison to non-persistent VDI, is the ability to customize and personalize desktops. It's part of what users have come to expect from a desktop interface — that when they make changes to their desktop, those changes will be there later. By contrast, non-persistent VDI just seems cheap and inferior.
However, persistent VDI requires resources. In this type of setup, the storage resource is often separate or loosely tethered to the set of desktops. Someone will have to manage how that storage is used, and that can trigger all sorts of additional costs.
In summary, if money is no object, you have a relatively static end-user base, and you have the resources for infinite storage, persistent VDI is the way to go. But if resource and cost efficiency is your principal goal, you may want to choose non-persistent VDI when it's possible.
Benefits And Disadvantages Of Non-Persistent VDI
Non-persistent VDI is created from a single “golden image” that just gets cloned or replicated according to user demand. VMware calls these cloned instances “linked clones” (see this VMWare article on ‘creating a linked-clone desktop pool). They are very easy to spin up, for example, on virtual machines.
Non-persistent VDI yields the largest benefits for scenarios where users should not be allowed to save anything, and the session is supposed to always revert to its original state.
A common reason for this is security. Cybersecurity is becoming a major priority for many businesses. Non-persistent VDI can play into an over-arching security strategy as individual employees or end users can't save possibly harmful files on the desktop. They can't set up connections requiring multiple sessions that might let some malware or hacking attempt in.
Because they're so generic, stateless VDI instances are also easy to erase. If one gets hacked, you simply reboot and start over. By contrast, if a persistent VDI instance gets hacked, you lose all of that customization, and it might be harder to manage from a security standpoint.
Scenarios For Persistent And Non-Persistent VDI
To get a better understanding of how this works, think about some of the most common uses of both of these types of Virtual Desktop Infrastructure.
Persistent Virtual Desktop Infrastructure is abundantly popular in static scenarios where individual end users are always the same and use the same workstations or report to the same locations day after day.
When you have long-term, full-time staffers, they want stability and consistency. They want to have their (virtualized) desktops that they can customize and keep in the particular ways that work best for them — and they want to be able to save files and folders. Anything less can be extremely frustrating.
On the other hand, some scenarios that work best for non-persistent VDI involve public workstations where the end user changes from one moment to another and you never really know who's logging on.
In these types of cases, persistent VDI can be an expensive liability. It doesn't make sense for a number of reasons. You don't want these random users customizing the dashboard in all sorts of possibly compromising ways — for example, uploading objectionable content and leaving it there — and you don't want the expense for something that's really not needed. A new end user who is only going in-session for a few minutes and will never be back doesn't need customization.
Customers can also choose from specific branded options. VMware offers something called VMware Horizon Viewfor virtual desktop management. Citrix offers Virtual Desktop Infrastructure as an alternative to its XenApp service that simply delivers Microsoft instances remotely. Citrix also offers three separate flavors of VDI. Customers can choose a non-persistent or a persistent type of Virtual Desktop Infrastructure, where a non-persistent type is called “pooled VDI” and simply pulls from an existing pool of desktop instances. Citrix also offers a third option called “static non-persistent VDI” that seems to work as a hybrid — while the user would always be redirected back to the same desktop, any customization will not be saved.
Think about any of these options as a way to streamline workflows for multiple end users and virtualize desktop functionality.