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Comparing AVD vs. VDI and how to start a migration plan

When organizations evaluate their existing business technologies, choosing a method to host and deliver virtual desktops is a critical decision. Find out how to make that decision.

Cloud-based virtual desktops such as Azure Virtual Desktop are rapidly replacing more traditional systems such as VDI.

Even so, replacing an existing VDI deployment with Azure Virtual Desktop (AVD) isn't necessarily the best option. There are pros and cons to each approach and the migration process to AVD can be complicated and error prone. As such, organizations must carefully consider whether they should migrate to Azure Virtual Desktop or if they are better off sticking with their existing VDI setup.

Comparing AVD vs. VDI

If an organization has decided that it may be worth moving from AVD to VDI, it's important for organizations to specifically compare AVD and VDI against one another. Lots of the benefits and challenges of virtual desktops are the same across VDI and AVD, so it's critical to pay special attention to the differences.

Evaluating Azure Virtual Desktop

One of the biggest advantages associated with AVD is that it is both flexible and scalable. It allows organizations to increase capacity on demand and reduce the number of virtual desktops just as easily. In other words, organizations can add or remove virtual desktops as the user count changes.

Another major benefit to using AVD is that it is accessible from anywhere and the virtual desktops can be used from a wide variety of endpoint types. While it is possible to make VDI-based virtual desktops remotely accessible, there are numerous security considerations that IT must set up. Azure Virtual Desktops natively support security features such as multifactor authentication, encryption and role-based access control. Never mind the fact that the Azure data center itself was created with security at the forefront of the design process.

One of the most significant advantages to using AVD is that Microsoft delivers it as a managed service. This means that an IT department can manage its virtual desktops through a centralized dashboard. It also means that IT doesn't have to worry about managing or maintaining the back-end infrastructure.

One of the most significant advantages to using AVD is that Microsoft delivers it as a managed service. This means that an IT department can manage its virtual desktops through a centralized dashboard.

Some of the biggest disadvantages of using AVD also apply to VDI environments. For example, the initial setup can be complex. Resource management and licensing are also well-known pain points. Another disadvantage is that the end-user experience is ultimately dependent on the quality of the user's internet connection. As such, these can't really help organizations decide AVD vs. VDI.

Putting aside the disadvantages that are common to both platforms, there are still some other disadvantages to consider before adopting AVD. One is that AVD is entirely dependent upon the Azure Cloud. In other words, if Microsoft were to experience an extended outage, all the virtual desktops would likely become inaccessible until the issue is resolved. However unlikely this may be, some outages have occurred with other Microsoft cloud services -- most notably, Microsoft 365 -- over the years. These have been relatively minor outages, but it's not too far-fetched to keep this in mind.

Another potential disadvantage is the cost associated with using Azure Virtual Desktops. Even though the cloud is often marketed as being a less expensive alternative to on-premises operations, those cost savings are not always realized once organizations factor in cloud usage and all the necessary licenses. An organization must proactively take steps to limit resource consumption to prevent the costs from becoming excessive.

A chart comparing VDI and DaaS as virtualization methods.

Evaluating VDI

As is the case for AVD, VDI deployments also present some unique advantages and disadvantages. One potential advantage is that it may cost less to operate an on-premises VDI deployment. If for example, all of an organization's VDI hardware and the corresponding software licenses are already paid for, then it may not make sense to abandon this existing investment in favor of a cloud-based environment that will incur significant monthly costs. Even if an organization wants to move to a cloud-based environment, it may make more financial sense to align the migration with the next hardware refresh cycle rather than doing it right away.

Another advantage to sticking with an existing on-premises VDI deployment is that it presumably works and meets the organization's needs. While AVD also works, it may take a considerable amount of post-migration fine-tuning to make it work as well as an existing VDI deployment.

One more advantage to using a VDI environment is that using one's own on-premises desktop virtualization offers more flexibility than what customers can expect from a cloud-based platform. IT teams are in full control of how the back-end infrastructure is configured and how to choose any desktop OS as needed with any unique configurations. Cloud providers often impose limitations in the name of security and supportability.

The main disadvantages to sticking with on-premises environments include complexity and supportability. It may be easier to get support and resolve problems in a cloud environment, though this is not necessarily the case in every situation.

A chart listing relevant features and determining factors of AVD and Windows 365.

How to plan an Azure Virtual Desktop migration from VDI

If the comparison of AVD vs. VDI leads to IT and management choosing to move to AVD, it's time to plan the migration. Organizations considering making the move to Azure Virtual Desktop should consider all aspects involved in the migration process.

Microsoft provides a tool called Azure Migrate that can assist in migrating various workloads and services to the Azure cloud. This tool can assist with virtual desktop migrations. When performing a VDI migration, however, Azure Migrate can't do everything on its own. A big part of the migration process involves assessing a VDI deployment. For this part of the process, Azure Migrate asks administrators to select a third-party assessment tool -- which is available from within Azure Migrate. Microsoft generally recommends using Lakeside SysTrack.

The assessment process requires IT to deploy agents to all virtual desktops to gather performance metrics. This will help the IT team size the virtual desktops in Azure, which is important from a cost management standpoint.

The agent will also compile an inventory of all the applications that are installed on users' virtual desktops. Remember, IT will typically have to migrate these applications along with the virtual desktops themselves.

Another important thing to consider regarding migration planning is that before an organization can migrate any virtual desktops, IT will need to create an Azure Virtual Network between the on-premises environment and Azure. The desktops are presumably configured to access services that reside on premises, including domain controllers, DNS services, network file shares, server-based applications or other resources. Moving virtual desktops to the cloud without first creating the necessary virtual network would lead to the virtual desktops losing the ability to access these resources.

Keep in mind that in addition to providing a network path between Azure and the on-premises network, IT will have to synchronize the existing Active Directory environment to Azure AD. Otherwise, Azure virtual desktops won't work correctly even though a path to the on-premises domain controller exists.

Some organizations ultimately decide to migrate some of their server-based applications to the cloud in parallel with their virtual desktop migrations. The reason for this is that moving virtual desktops to the cloud while leaving applications on premises increases the latency associated with using those applications.

Yet another factor to consider is that most AVD migrations require desktop images to be re-created. In doing so, IT admins may have to change the way that applications are provisioned and how the virtual desktops connect to various services. They may also need to adjust the security components and controls that they use.

Finally, keep in mind that admins must change the way that user profiles are stored. Organizations typically keep roaming or mandatory profiles on a server that is in close proximity to the desktops. In the case of an AVD migration, IT will need to use PowerShell to convert existing user profile virtual disks to FSLogix profiles.

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