Persistent vs. Concurrent Virtual Desktops

If a business is considering new technology, the solution should fit the needs of the business (which might include mitigating risk or meeting compliance standards), make life easier for IT (less help desk calls) and be something that users want to use. If the solution is not hitting on all three of these things, the likelihood of success decreases.

It’s easy to see how a flexible solution can be advantageous, and virtual desktop solutions are no different – they are not one-size-fits all. For example, IT always wants to balance what is easy for users to consume with what’s easy for IT groups to manage. After all, companies move to VDI solutions because of all the management efficiencies they gain. Among other things, the key to achieving these goals is to choose the right deployment option for your needs, specifically deciding between persistent vs. concurrent desktops. One approach isn’t necessarily better than the other as each is ideal for different use cases and solves different business challenges.

Persistent Desktops

One option to deploy virtual desktops is a persistent, or dedicated, model. With this method, the environment administrator builds a virtual desktop for every user. The first time a new user logs on, they are automatically assigned any available virtual desktop. For subsequent logins, individual users always get that same desktop machine each and every time. If desired, administrators can also explicitly assign a specific machine to a specific user. In either case, if a user does not log on to their desktop for some period of time, that desktop sits idle as it is not available to any other user.

This approach provides a highly customizable user experience where each individual can personalize their desktop to their preference, install applications (as allowed per corporate policy), create desktop shortcuts, etc. Because the user gets the same desktop every time, all settings, and even documents left open when they logged off, will be exactly as they left it. It’s as if a user was working with a traditional desktop – just now it’s available from any device, anywhere, instead of static to a specific physical machine.

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Concurrent Desktops

Another option is a floating desktop pool, which delivers a concurrent desktop to users. When a user logs in to their virtual desktop with this method, a request is made to a replica of the golden image template, or “parent.” This parent is a locked-down desktop image from which all other virtual desktops are created. When a user makes a logon request, the system grants access to a snapshot of the parent image. Any changes the user makes to their desktop will not affect the parent image.

Virtual Desktop Administrators can then set the action taken when a user logs off. The virtual desktop can either be refreshed to the original snapshot or the existing snapshot can be recomposed – which deletes the snapshot and creates an entirely new one.

Refreshed Desktops: This effectively returns the virtual desktop to the state of the original pristine snapshot, erasing any changes made during the user’s session. This ensures all users are always on a known good desktop configuration, which, among other things, makes troubleshooting for IT teams issues easier. However, with this approach desktops will retain the configuration of the original snapshot and not reflect any changes made to the Golden Image.

Recomposed Desktops: Configuring the action to delete the existing snapshot and create a new one also results in a pristine state every time, but adds a bit of time to the process since a new snapshot is generated with each login. In this case, because a new snapshot is created each time, any Operating System or application changes from the parent are applied at the user’s next login.

An overarching benefit of either approach to concurrent desktops is that because the user’s desktop is essentially wiped clean each time, any virus the desktop encounters will be removed upon log off (unlike with traditional desktops or persistent virtual desktops). 

If you need persistency in a floating pool (i.e. the ability for users to make customizations), additional technologies can be applied so that user and profile data is redirected and saved outside of the desktop to a persistent disk. The profile data on this persistent disk is applied to the virtual desktop when the user logs on. This configuration is more complex, however it ensures users always have the latest and greatest security patches and updates while keeping user data consistent with each login. With this approach, users’ data, their profiles and their applications are no longer “living” on individual desktops and can be managed independently.

As profile management and application layering solutions continue to improve, persistent floating desktops are becoming much more commonplace as it allows for the greatest amount of flexibility. Organizations that don’t want to take on the increased management complexities are turning to fully managed DaaS providers to get the full advantages of concurrent virtual desktops.

Use Cases

Each VDI implementation is different as is each use case. If your business handles sensitive information, such as personal health information (PHI) or credit card numbers, you may get peace of mind knowing that your users’ virtual desktops are reverted back to a clean image after each logoff. If a user inadvertently saved sensitive data to their virtual desktop, it would be destroyed at logoff. In this scenario, a floating desktop pool might be best.

Since users can effectively use any image, floating pools also work well with shift work. Instead of deploying a virtual desktop for each user (and incurring the associated costs), you can deploy a desktop for only those on shift. Any change that particular worker makes (or anything they inadvertently save to the wrong location) will be wiped at the end of their shift, leaving a clean desktop for the next shift.

However, not all use cases call for a fresh OS image at each login. For office workers who may work with a non-standard set of applications and documents, persistent desktops can be a great fit. They get the benefit of having a desktop that is always available, no matter where they are, while still having access to the specific documents, data and applications they need.

Choosing Between Persistent & Concurrent Desktops

It’s important to remember that this is not an all-or-nothing decision. Many companies have mixed use cases where they deploy both persistent and concurrent desktops to different departments.

When planning your virtual desktop initiative, detail your particular use cases and what features would best fit each group. Do they need virtual desktops that are very similar to how traditional desktops work but accessible from anywhere on any device? Would you feel more comfortable from a security perspective if users have limited ability to make changes to their desktops? A DaaS Engineer can help you think through your needs and recommend which approach or mix of approaches would be best for your use cases.

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