Introduction to EUC

Virtual desktop infrastructure (VDI) is a desktop virtualization technology wherein a desktop operating system, typically Microsoft Windows, runs and is managed in a data center. The virtual desktop image is delivered over a network to an endpoint device, which allows the user to interact with the operating system and its applications as if they were running locally. The endpoint may be a traditional PC, thin client device or a mobile device.

The concept of presenting virtualized applications and desktops to users falls under the umbrella of end-user computing (EUC). The term VDI was originally coined by VMware and has since become a de facto technology acronym. While Windows-based VDI is the most common workload, Linux virtual desktops are also an option.

How the user accesses VDI depends on the organization's configuration, ranging from automatic presentation of the virtual desktop at logon to requiring the user to select the virtual desktop and then launching it. Once the user accesses the virtual desktop, it takes primary focus, and the look and feel are that of a local workstation. The user selects the appropriate applications and can perform their work.

VDI may be based on a server or workstation operating system. Traditionally, the term VDI has most commonly referred to a virtualized workstation operating system allocated to a single user, but that definition is changing.

Each virtual desktop presented to users may be based on a 1:1 alignment or a 1:many ratio, which is often referenced as multi-user. For example, a single virtual desktop allocated to a single user is considered 1:1, but numerous virtual desktops shared under a single operating system is a hosted shared model, or 1:many.

A server operating system can service users as either 1:1 or 1:many. Where a server operating system is the platform for VDI, Microsoft Server Desktop Experience is enabled to more closely mimic a workstation operating system to users. Desktop Experience adds features such as Windows Media Player, Sound Recorder and Character Map, all of which are not natively included as part of the generic server operating system installation.

Until recently, a workstation operating system could only service users as 1:1. However, in 2019, Microsoft announced the availability of Windows Virtual Desktop (WVD), which enables multi-user functionality on Windows 10, which was previously only available on server operating systems. Thus, Windows 10 now has true workstation multi-user functionality. WVD is only available on Microsoft's own cloud infrastructure, Azure, and there are stringent licensing requirements that make it inappropriate for all but enterprise organizations.

Each endpoint device must install the respective client software or run an HTML5-based session that invokes the respective session protocol. Each vendor platform is based on a remote display protocol that carries session data between the client and computing resource:

High-definition user experience (HDX) from Citrix is largely an umbrella marketing term that encompasses ICA, EDT and some additional capabilities. VMware user sessions can be based on Blast Extreme, PCoIP or RDP. Microsoft Remote Desktop can only use RDP.

The display protocol, or session protocol, controls the user display and multimedia capabilities, and the specific features and functionality of each protocol vary. PCoIP is licensed from Teradici, whereas Blast Extreme is VMware's in-house protocol. In addition, EDT and Blast Extreme are optimized for User Datagram Protocol (UDP).

The session protocols listed above minimize and compress the data that is transmitted to and from the user device to provide the best possible user experience. For example, if a user is working on a spreadsheet within a VDI session, the user transmits mouse movements and keystrokes to the virtual server or workstation, and bitmaps are transmitted back to the user device. The data itself does not populate the user display, but instead shows bitmaps representing the data. When a user enters additional data in a cell, only updated bitmaps are transmitted.

VDI requires several distinct technologies working in unison to successfully present a virtual desktop to a user. First and foremost, IT must present a computing resource to the user. Although this computing resource can technically be a physical desktop, virtual machines are a more common choice.

For on-premises deployments, a hypervisor hosts the virtual machines that will deploy as VDI. Citrix Virtual Apps and Desktops and Microsoft RDS may be hosted on any hypervisor, whereas VMware Horizon has been engineered to run on its ESXi hypervisor. When organizations must use virtual graphics processing units (vGPUs) to support highly graphical applications such as radiographic imaging or computer-aided design (CAD), it's common to use Citrix Hypervisor (formerly XenServer) or VMware ESXi.

A mechanism for mastering and distributing VDI images is necessary, and there is significant complexity involved with these processes. Depending on enterprise requirements, IT may employ one gold image for all VDI workloads or numerous gold images. Minimizing the number of images decreases administrative effort, as each image adds exponential overhead. IT must open gold images, revise them with Windows updates, base applications, antivirus and other changes, and then subsequently re-enable them.

Storage resources can be significant and may represent the single most expensive aspect of VDI, especially when each virtual machine is allotted significant disk size. IT may elect thin provisioning, causing the virtual machine to use the minimum amount of disk space and then expand as necessary. However, close monitoring of actual storage requirements is necessary to ensure that storage expansion does not exceed actual space. To combat this possibility, organizations may choose thick provisioning, which causes the maximum amount of space to be fully allocated.

IT often uses layering technologies in conjunction with VDI images. By providing a non-persistent virtual desktop to users and adding layers for applications and functionality, IT can customize a virtual desktop with minimal management. For example, IT may append an application layer suitable for a marketing department for those users, whereas an engineering department would require a distinct application layer with CAD or other design applications.

VDI requires enterprise data to traverse the network, so IT must secure user communications via SSL/TLS 1.2. For example, Citrix strongly recommends using its Gateway product (formerly NetScaler) to ensure that all traffic traverses the network securely.

Converged infrastructure and hyper-converged infrastructure (HCI) products address the scalability and cost challenges associated with virtual desktop infrastructure. These products bundle storage, servers, networking and virtualization software -- often specifically for VDI deployments. Both Nutanix and VMware lead the market share for HCI and can serve as the platform for Microsoft RDS, VMware Horizon and Citrix Virtual Apps and Desktops.

VDI administrators may deploy non-persistent or persistent desktops. Persistent virtual desktops have a 1:1 ratio, meaning that each user has their own desktop image. Non-persistent desktops have a many:1 ratio, which means that many end users share one desktop image. The primary difference between the two types of virtual desktops lies in the ability to save changes and permanently install apps to the desktop.

With persistent VDI, the user receives a permanently reserved VDI resource at each logon, so each user's virtual desktop can have personal settings such as stored passwords, shortcuts and screensavers. End users can also save files to the desktop.

Persistent desktops have the following benefits:

However, persistent VDI also comes with drawbacks:

Non-persistent VDI spins up a fresh VDI image upon each login. It offers a variety of benefits, including:

The most commonly cited drawback for non-persistent VDI is limited personalization and flexibility. Customization is more limited for non-persistent VDI, but IT can layer a mechanism to append the user profile, applications and other data at launch. Thus, non-persistent VDI presents a user with a base image with unique customizations.

VDI is a powerful business technology for well-aligned use cases. To decide whether VDI is good fit, organizations should carefully assess their users from the perspective of what they do and where they work.

Generally, local and remote users (who perform work on desktops from a centrally located site) could benefit from VDI. Mobile users (who work from a variety of different locations) are not always a good fit for VDI; organizations should evaluate these situations on a case-by-case basis. The same goes for roaming users, or users who split their time between local or remote sites.

Evaluate the type and location of workers to determine whether VDI is a good fit.

Organizations must also evaluate how their users complete their work, such as the applications, resources and files they use. Generally, employees fall into four categories:

There are other use cases that work well with VDI:

VDI as a platform has many benefits, including:

Main benefits of VDI include simplified management and reduced cost.

When VDI first came to prominence about 10 years ago, some organizations implemented VDI without a justified business case. As a result, many projects failed because of the unexpected back-end technical complexities, as well as a workforce that wasn't fully accepting of VDI as an end-user computing model. It's also important to test a VDI deployment to ensure that the organization's infrastructure and resources can achieve acceptable user experience levels on virtual desktops.

Costs such as hardware upgrades, maintenance fees and licensing can add up with VDI.

Here are some potential drawbacks of implementing VDI:

Potentially poor user experience. Without sufficient training, providing the user with access to two desktops (i.e., the local desktop and the virtualized desktop) may be confusing and result in a poor user experience. For example, if users attempt to save a file from the virtual desktop, they may search for it in the incorrect location. This may result in additional support requests to find missing files that were simply archived on the incorrect desktop.

Additional costs. Organizations should review financials associated with VDI in depth. While there are monetary savings associated with extending the life of endpoint hardware, the additional costs for IT infrastructure expenses, personnel, licensing and other items may be higher than expected.

Although storage costs have been declining, they can nonetheless cause VDI to become cost prohibitive. When a desktop runs locally, the operating system, applications, data and settings are all stored on the endpoint. There is no extra storage cost; it's included in the price of the PC. With VDI, however, storage of the operating system, applications, data and settings for every single user must be housed in the data center. Workload capacity needs, and the cost required to meet them, can quickly balloon out of control.

Complex infrastructure. VDI requires several components working together flawlessly to provide users with virtual desktops. If any of the back-end components encounter issues, such as a desktop broker or licensing server automatically rebooting or a VM deployment system running out of storage space, then users cannot make virtual desktop connections. While the VDI vendor's monitoring features offer some details regarding system issues and related forensics, large environments in particular likely need a third-party monitoring tool to ensure maximum uptime, which further adds to costs.

Additional IT staff. Maintaining staff to support a VDI environment can be difficult. In addition to recruiting and maintaining qualified IT professionals, ongoing training and turnover are very real challenges that organizations face. Furthermore, when organizations undertake new projects, they may need to hire external consultants to provide architectural guidance and initial implementation assistance.

Licensing issues. Software licensing is an important consideration. In addition to the initial procurement for VDI licensing, ongoing maintenance and support agreements affect the bottom line. Moreover, Microsoft Windows workstation and/or server licensing is required and may represent an additional cost. VDI can complicate vendor software licensing and support because some licensing and support agreements do not allow for software to be shared among multiple devices and/or users.

Reliance on internet connectivity. No network, no VDI session. VDI's reliance on network connectivity presents another challenge. Although internet connectivity is quickly improving throughout the world, many locations still have little or no internet access. Users can't access their virtual desktops without a network connection, and weak connectivity can cause a poor user experience.

VDI technologies from Citrix, Microsoft, VMware and others address business and technical requirements that enable users to access consistent virtual desktops remotely. Business needs and user experience should be weighed against resource requirements, costs and technical complexities to ensure that VDI is the right platform for a given enterprise.

Remote Desktop Services (RDS) and VDI are both ways to deliver remote desktops to users. Like VDI, RDS enables users to access desktops by connecting to a VM or server that is hosted in a local data center or in the cloud. The desktop environment, applications and data all live on that VM or server. There are differences between RDS and VDI, however.

RDS was originally called Terminal Services, which was a feature from Windows' legacy operating system, Windows NT. Citrix wrote and licensed the code for Terminal Services. RDS is limited to Windows Server, which means that users can only access Windows desktops. However, VDI is not limited to a single operating system or application architecture.

To enable RDS for a user, IT must run a single Windows Server instance on hardware or a virtual server. That one server simultaneously runs every user's instance. With VDI, each user is linked to its own VM that also must have its own license for the OS and applications.

For users to access that instance, they must connect to a network and their client devices must support Remote Desktop Protocol, a Microsoft protocol that supplies a user with a graphical interface. Using that interface, a user can connect to another computer over a network connection.

For the most part, all RDS users are presented with the same OS and applications. Windows Server 2016 and later versions allowed for personal session desktops to have some persistency, however.

RDS supports many users. Because each license is linked to a user via Microsoft's Client Access License, RDS licensing and administration can be simpler than VDI. RDS works well for organizations that need to support standard desktop applications such as Microsoft 365 or email.

VDI, however, is a better fit under the following circumstances:

There are two principal mechanisms for delivering a virtual desktop to a user: virtual desktop infrastructure and desktop as a service (DaaS). The difference between these two mechanisms is simply a matter of who owns the infrastructure.

The differences between VDI and DaaS.

With VDI, the business locally creates and manages the underlying virtualization and resulting virtual desktops. This means the business itself owns and operates the VDI servers, takes charge of creating and maintaining all the virtual desktop images, and so on. By deploying VDI, a business exercises complete control over the virtual desktop environment. This can be a preferred alternative for any business that is subject to stringent compliance regulations or must provide a strong security posture. However, the additional costs of buying, installing and maintaining VDI servers and software may be prohibitive for some small businesses.

With DaaS, a third-party provider creates and manages the virtualization environment and virtual desktops. Most commonly, this includes not only the virtual desktop, but also apps and support. The outside provider owns and operates the VDI servers and controls the creation and provisioning of virtual desktop images. In effect, the business simply "rents" virtual desktops from the provider who provisions the requested instances and makes them available to users.

DaaS is often thought of as "VDI in the cloud" and is usually presented as a cloud service. This can be a preferred alternative for any business with limited IT capabilities where deploying VDI is undesirable, or when the business is better suited to handling the monthly recurring bill for virtual desktops.

IT can more easily scale up and down desktops with DaaS by adding or removing licenses rather than making changes to the infrastructure itself. This can be beneficial for companies that are growing rapidly or experience usage spikes during certain times of the year, such as Black Friday. DaaS may also better support organizations with GPU-powered applications by providing a more attainable way to access expensive hardware.

DaaS does have drawbacks, however. While vendors tout support for simple or common apps such as Microsoft Office, the reality is that business application integration -- including databases, file servers and other resources -- is extremely complex. As such, the implementation of true and useful DaaS products is often a lengthy, complex process.

Organizations that transition from on-premises VDI to DaaS could choose between a few different methods. Organizations could use the "lift and shift" method for VDI workloads, which includes moving applications without redesigning them or changing workflow. A more comprehensive method includes rethinking strategies, as well as reviewing cloud offerings, which results in a more comprehensive and updated technology offering.

In the early 2000s, VMware customers began hosting virtualized desktop processes with VMware and ESX servers, using Microsoft Remote Desktop Protocol in lieu of a connection broker. During VMware's second annual VMworld conference in 2005 the company demonstrated a prototype of a connection broker.

VMware introduced the term 'VDI' in 2006, when the company created the VDI Alliance program and VMware, Citrix and Microsoft subsequently developed VDI products for sale. Virtual desktops were a somewhat hidden but optional capability of Citrix Presentation Server 4.0 and XenDesktop was later released as a standalone product.

VMware released its VDI product under the name Virtual Desktop Manager, which later was renamed View, then Horizon. Citrix's products, XenDesktop and XenApp, were later rebranded to Citrix Virtual Apps and Desktops.

Licensing was a significant hurdle for early VDI deployments, mainly due to Microsoft's Virtual Desktop Access (VDA) requirement. Organizations with Windows virtual desktops that were hosted on servers needed to pay $100 per device per year for VDA licensing. Microsoft Software Assurance (SA) licensing included VDA, but only for Windows devices. This meant that companies with tablets, PCs and smartphones that weren't manufactured by Microsoft were required to pay significant licensing fees.

Many organizations found a workaround by using Windows Server as the VDI's underlying OS. This prevented organizations from paying exorbitant licensing fees because the Windows Server license was a one-time fee; the VDA license was an annual cost, plus the cost of the Windows Server license.

In 2014, Microsoft allowed Windows licenses to be assigned per user rather than per device, which alleviated the costly problem of VDA licensing.

DaaS, a desktop virtualization model in which a third-party cloud provider delivers virtual desktops via a subscription service, began to gain traction in the mid-2010s. Amazon released one of the first DaaS products in 2014, offering single-user Windows Server 2012 as the OS. Other vendors, including Citrix, VMware and Workspot followed suit with their own DaaS products.

In 2019, Microsoft brought more changes to the VDI industry when it released Windows Virtual Desktop, a DaaS offering that runs on the Azure cloud and provides a multiuser version of Windows 10. Organizations must pay for Azure subscription costs, but the DaaS offering is included with a Windows 10 Enterprise license.

Looking to break into the VDI field? Read our feature about becoming a VDI engineer.

The VDI market is growing exponentially due to a variety of factors, including increased adoption of BYOD programs and a greater need for a mobilized workforce. Cloud-based VDI, or DaaS, is in particularly high demand. In 2016, the cloud-based VDI market was worth $3.6 million and it is estimated to reach over $10 million by 2023, according to Allied Market Research.

The COVID-19 pandemic generated further interest in DaaS due to the suddenly heightened need for users to be able to work anywhere. During the COVID-19 pandemic, for example, DaaS allowed many organizations to more easily transition to a work-from-home environment due to the desktop virtualization model's scalability and ease of deployment.

Many organizations are embarking on their journey to the cloud, and incorporating VDI requirements is an important aspect of architecting the next-generation infrastructure. Many experts believe that DaaS will be a popular deployment method in the future because it is a subscription-based SaaS model, a model that many software providers have moved to.

The cloud subscription model makes sense from a vendor perspective, as well. Subscriptions generate a consistent, recurring revenue stream rather than one-time sales transactions that create irregular bumps in revenue. Vendors can more easily market consumption-based services because there are attractive benefits, such as lower maintenance fees and upfront costs.

There are three key players in the VDI market: Citrix, Microsoft and VMware. Of these, Citrix Virtual Apps and Desktops holds the largest market share, followed by VMware Horizon and subsequently Microsoft Remote Desktop Services (RDS).

Compare the support, pricing and other components of DaaS vendors.

Citrix and Microsoft first came to market with virtualized apps and shared desktops based on server-based computing. They subsequently offered VDI workloads based on workstation operating systems, whereas VMware initially launched VDI and then later offered virtualized apps.

The VDI market also includes other vendors that can often be more affordable than the major, tried-and-true vendors. These options include flexVDI, NComputing and Leostream.

Many on-premises VDI vendors also have a DaaS offering. For example, Citrix offers Citrix Managed Desktops, VMware offers Horizon DaaS and Microsoft released Azure-based Windows Virtual Desktop in 2019. Amazon also has a DaaS offering, Amazon WorkSpaces.

By Drew Robb -@August 11, 2022 3:13 PM (EST)

Citrix and VMware have been among the leading VDI pioneers and are now competing head-to-head in a related market, DaaS. Both vendors are well respected in this growing area.

First, some background. Virtual Desktop Infrastructure (VDI) technology was developed many years back as a way to virtualize the desktop. It enables access to enterprise systems from almost any PC, smartphone, or tablet. Servers, applications, files, and services are made available to authorized users. How? By transferring desktop workloads from the device to centralized servers – the device then becomes a means of connecting a work platform. It does not contain the applications; the device is solely a means of accessing and viewing the data.

VDI technology has come a long way in recent years. While some still deploy it using in-house hardware, the market has shifted toward the Desktop as a Service (DaaS) model. DaaS provides virtual desktop services as well as applications that are aimed at enabling a seamless remote workforce, allowing organizations to raise productivity and efficiency and heighten security, and to remove many of the complexities involved in VDI. Instead of managing the underlying hardware in the data center, those functions can be pushed into the cloud and handed off to an external provider.

Citrix and VMware both provide strong VDI and DaaS offerings. But which is best for your company?

Also see: Top Cloud Companies

Citrix offers well-established VDI and DaaS platforms. The emphasis, these days, is on Citrix DaaS (formerly known as Citrix Virtual Apps and Desktops). It provides either cloud-based or on-premises desktop virtualization to Windows, Linux, and web applications and ensures desktop delivery from multiple devices over any network.

The Citrix solution comes with plenty of security features. Built-in HDX technology helps with delivery of multimedia and graphics applications without the lag times sometimes experienced with VDI. A central cloud console provides management of-premises workloads alongside cloud-based DaaS environments. The solution is available via a monthly subscription.

VMware also offers both VDI and DaaS options. Since the market has gravitated toward DaaS, the company is giving the heaviest emphasis to its VMware Horizon DaaS platform. Features include multi-tenancy for greater security, a unified platform to provision and manage multiple workspaces, as well as geographic scalability across data centers and plenty of cloud flexibility – it is deployable on private, public, or hybrid clouds. VMware offers an advanced Graphics Processing Unit (GPU) as a desktop feature that supports graphic designers, architectural and mechanical design professionals, and similar power users that rely on high-quality graphics. There are many flavors available. It includes:

Both Citrix and VMware have a good track record in the marketplace, but VMware gets the nod due to its DaaS features being a little more comprehensive than those of Citrix.

Also see: Why Cloud Means Cloud Native

Citrix is relatively easy to deploy and lets users spin up more desktops as needed. It can run on-prem, in the cloud, or in a hybrid configuration. User reviews tend to place Citrix a little ahead of VMware in ease of deployment and technical support. Ease of use is an area the company has regularly been addressing via updates and upgrades.

VMware has enough flexibility so users can deploy VDI and manage the infrastructure internally or in the cloud, whether public, private, hybrid and multi-cloud deployments. It includes a cloud-based console and SaaS management services. This makes it easier to automate the provisioning and management of virtual desktops and apps and deliver personalization. Horizon 7 includes a Workspace Environment Management (WEM) platform that allows users to manage, monitor, and expedite the delivery of applications, desktops, and infrastructure across their environments, and ensures that data is secured back in the data center.

Per user feedback, Citrix is the winner in this category.

Citrix DaaS is optimized for Microsoft Azure integration. As such, it supports Microsoft Teams, Skype for Business, and other tools. Additionally, it supports peripherals such as monitors, USB devices, and webcams. But it can operate in the cloud or on-premises and with Windows, Linux, and most web applications. As well as Azure, the company lists integration with Amazon Web Services, Microsoft App-V, VMware vSphere, and more.

VMware Horizon has deep integration into the VMware technology ecosystem, including vSphere and vCenter. It also integrates with Azure and other cloud services. Users rate its integration capabilities higher than Citrix.

Both solutions offer plenty of integration options, and while VMware is more focused on its own ecosystem, user ratings give it a narrow win in this category.

Citrix DaaS comes with multi-factor authentication, real-time monitoring, session watermarking, password management, and protection of access permissions and policies based on location or device of employees.

VMware Horizon DaaS provides desktop-level OS anti-virus and anti-malware protection, as well as plenty of other security features for secure remote access from any device. A close partnership with security firm Carbon Black is built around a zero-trust model across users, apps, and endpoints. Device state, location, and user behavior are used to determine which, if any, corporate resources users can access. Carbon Black brings to the table endpoint security, AV, Behavioral Endpoint Detection and Response, and more.

VMware wins on security.

Citrix keeps pricing fairly straightforward. Citrix Daas Standard is $10 per user per month. The Advanced Plus version is $13; this adds hybrid cloud and on-prem provisioning and the ability to run apps on both. Citrix DaaS Premium is $20, which comes with additional monitoring, imaging, and security tools. Premium Plus is $23 and that includes performance analytics and security analytics features.

VMware Horizon pricing is harder to decipher. The pricing is $3,116 as a one-time cost for the basic VMware Horizon version. But the versioning gets a little complex. The next version is the same price but includes 10 users. The enterprise-class version is $4,362 for 10 users. It is difficult to unearth out how this all works, how much it is for more users, or how many users the basic version includes. Company documentation is lengthy but murky on the subject. The best strategy is likely to contact a sales rep.

However, it is likely that there are scenarios where VMware works out cheaper. But for simplicity of pricing, Citrix wins. This is supported by user feedback. Users tend to rate the flexibility of pricing in Citrix higher than VMware.

Which solution is best? As usual, the answer is: it all depends. For on-prem workloads, Citrix is probably the right way to go. The company built its VDI business primarily in the on-prem space. It continues to excel there. Those security teams dealing with compliance standards and regulatory challenges in-house will find Citrix a good choice. That said, its DaaS and cloud desktop capabilities are strong, too. It offers a wide range of features to boost productivity in a secure way.

But VMware’s cloud focus puts it a little ahead on cloud deployments. Some users note occasional issues on Citrix DaaS when accessing some enterprise applications remotely, while others mention connection issues. VMware appears to suffer less from such problems.

Those organizations that have already invested in the VMware ecosystem will tend to gravitate toward Horizon DaaS. VMware also tends to score well on robustness, security, and scalability for over 50 seats, and cost for larger deployments. Its security features are hard to beat, although Citrix does a good job of security. Similarly, management functionality for large deployments favors VMware.

Bottom line: For large deployments, VMware is probably the best choice. For small and mid-sized deployments, the choice of Daas is heavily dependent on the specific environments. And for on-prem VDI, Citrix is the way to go.

As remote work has become more common, desktop virtualization -- and how to implement it -- has become an increasingly important decision for IT teams.

One way to deploy virtual desktops is desktop as a service (DaaS), where desktop OSes run inside VMs on servers in a third-party cloud provider's data center. Organizations can also implement VDI -- which entails building out their own virtualization infrastructure and running desktop OSes on on-premises servers -- or stick with traditional desktops.

DaaS outsources the work of hosting virtual desktops to a third-party provider. It does not require a substantial initial investment like VDI does, so DaaS stands out for its easy and inexpensive setup. Still, IT administrators should be aware of all the pros and cons of desktop as a service -- not just the cost -- to assess whether it is the best fit for their organizations.

One of the most significant advantages of DaaS is that there are lower upfront costs than VDI or regular desktops. VDI requires a costly investment in infrastructure to get started, whereas DaaS is typically priced on a per-user basis. Organizations that want to test virtualization can turn to DaaS and skip the costs and labor of building VDI when they may want to change their approach to desktop virtualization years down the road. The subscription model makes the costs involved in DaaS more predictable over the long term as well.

DaaS can also reduce license costs because it makes it easy to provision and deprovision virtual desktops based on when users need them. For startups that may want to onboard employees quickly, it can be helpful to be able to scale up simply and inexpensively with DaaS. Likewise, the scalability of desktop as a service can have cost benefits for organizations that employ seasonal workers. Once the season is over and seasonal employees leave, the virtual desktops they used can be deprovisioned easily, eliminating the license costs for those virtual desktops.

The scalability of DaaS is also beneficial on a logistical level for organizations and their IT teams. If an organization wants to scale up, IT can update the DaaS subscription instead of having to adjust the VDI capacity by increasing virtual resources with additional hardware. This is especially helpful for organizations that don't know what scale they want; DaaS can adjust to fluctuations in virtual desktop numbers without requiring any reworking.

DaaS also offers flexibility in the variety of endpoints cloud providers can easily support out of the box. No matter what type of device a user chooses to work on, the desktop environment is identical, as long as it has the necessary display resolution and remote desktop client software. DaaS generally offers the same UX as VDI, but the ability to choose from a wider range of endpoints and locations to work from and maintain an acceptable desktop environment can result in a better experience for end users.

Desktop as a service is available from anywhere, on any device. Because the virtual desktops are hosted in the cloud, they are accessible anywhere, as long as power and internet connectivity are available. With VDI, on the other hand, users must connect to their organization's corporate network directly or via a VPN to access their virtual desktops, which requires further security considerations.

The rise of remote work has highlighted the usefulness of DaaS for organizations that want to ensure business continuity through circumstances such as the COVID-19 pandemic. DaaS' ability to support a variety of endpoints is especially helpful for facilitating remote work. Regardless of whether users have PCs at home, they are able to access a virtual desktop with DaaS.

Some DaaS providers offer browser accessibility. This is a secure and simple way for users to access DaaS. Rather than installing the virtual desktop, a user can log in to a browser-accessible virtual desktop through any browser that the DaaS provider supports. Some examples of this option include the Web Access feature in Amazon WorkSpaces, Azure Virtual Desktop web client and DesktopReady.

Setting up DaaS is easy for IT. The most critical step is choosing the best DaaS provider to meet the organization's needs.

DaaS is an easier option for IT after setup as well. To successfully deploy and maintain VDI, IT departments must have the skill set and sufficient employees to stay on top of updates, data traffic and troubleshooting. DaaS providers have the resources and expertise to reliably manage many of these concerns, enabling IT teams to focus on addressing issues that are more specific to their organizations.

This can also provide security benefits. IT has less control over security with desktop as a service, but a DaaS provider likely has more up-to-date tools and knowledge, which can help IT manage and prevent any issues.

While DaaS is less expensive than VDI in terms of initial investments, over time, the subscription costs that come with DaaS may accumulate to be higher than the upfront costs of VDI.

Additionally, depending on the licensing models that a vendor offers, DaaS can have higher license costs to account for the effort of hosting the virtual desktops. Most DaaS providers bundle the OS license with the cost of the virtual desktop, but organizations must weigh their options and keep these factors in mind to ensure that desktop as a service is the best approach financially. Pricing for DaaS is still more predictable and consistent than for VDI, but it's not necessarily less expensive in the long term.

Another con of DaaS is that the one-size-fits-all approach also might not be ideal for every organization. Security and compliance regulations vary depending on the organization, so finding a DaaS package that fits perfectly can be difficult. Because organizations build it in-house, VDI enables IT to make more customizations -- such as disabling certain services for users -- to meet compliance standards and ensure VDI security. If an organization with strict compliance regulations wants to use DaaS to implement virtual desktops, choosing a provider that prioritizes these standards is vital.

For example, Evolve IP Workspaces is a DaaS provider that is third party-audited to meet compliance standards, such as HIPAA or GDPR. Providers that don't specifically take certain compliance standards into account should allow IT to check compliance measures or control the hypervisors' configurations and customize features.

Some DaaS packages won't have everything an organization might want. Different vendors offer different levels of customizability, and some offer more advanced management capabilities than others.

Desktop as a service offers little control over updates and security in general, which can lead to problems that IT cannot directly address. Many of these issues stem from the hosting concerns that come with using a public cloud. For example, if the public cloud that hosts the virtual desktops has an outage, an organization's productivity comes to a total halt.

Security is a significant factor in both the pros and cons of DaaS. Because having all resources in a single location -- such as a DaaS vendor's public cloud -- can help security, DaaS might seem like the most secure desktop virtualization option. Additionally, some organizations might prefer the security that a vendor can guarantee rather than having to trust IT staff to maintain a perfect security posture. However, some IT teams might be better prepared to handle their organization's unique security strategy than a third-party provider, and admins must consider cloud security concerns with DaaS.

Not having full control over connectivity can put organizations in situations they are unable to do anything about as well. If there's a connectivity issue, IT has less insight into the network and must wait on the provider to fix the problem. And, while UX might be better and easier to ensure with DaaS, if there are UX issues, the IT team can't handle them directly.

Organizations that rely on desktop virtualization or are considering a transition to this technology should learn about Microsoft's virtual desktops options: Windows 365, announced in October 2021, and Azure Virtual Desktop.

Microsoft supports both services with its Azure cloud, but there are still some massive differences between them. For that reason, it's important to compare Microsoft Windows 365 and Azure Virtual Desktop (AVD), formerly Windows Virtual Desktop, based on features, licensing, support and other factors.

Windows 365's virtual desktops function as Cloud PCs, a single-user desktop application that uses Azure for virtual desktop deployment and storage. It resides in Microsoft's Azure cloud and is fully managed by Microsoft. Microsoft charges a fixed licensing cost per user per month -- similar to leasing a physical PC -- so customers pay for it whether it is in use for 50 or 500 hours. For this reason and a few others, Azure Virtual Desktop is more flexible and may be more efficient for large organizations.

Windows 365 has two core licensing options: Business and Enterprise. There are also four sub-options that these cores can be broken into -- basic, standard, premium and custom.

The Enterprise option does not have the 300-user limit that Business does, and both have the same price per user.

Another critical feature of Windows 365 is that it runs in a Microsoft Managed Azure subscription, which adds the following considerations to the decision:

Windows 365 has the following cost and licensing requirements as well:

Azure Virtual Desktop differs from Windows 365 in many ways. It still provides a virtual desktop benefit to the user but in a more flexible manner. This flexibility comes with a greater need for administration and a larger workload for IT professionals.

Organizations can deliver Azure Virtual Desktop as a personal or pooled desktop.

Azure's personal desktop functions similarly to Windows 365 Cloud PCs but offers the flexibility of pricing 'as you go.' It also allows for Windows 10 or 11 multiple user sessions. With the personal desktop approach, IT can do the following:

The pooled desktop, or personal host pool, is a collection of nodes that an app runs on with a one-on-one relationship -- user to desktop. This approach is ideal for resource-intensive workloads. For instance, if a particular project has some compute-intensive requirements such as 3D design, IT can create a pool of nodes with those requirements and assign them to users. The settings, profile and data changes are still present after logout. IT can create these nodes manually or in batch and organize them in any way it needs. There is no limit to the number of pools. IT can easily scale published pool desktops, allowing the admin to add or reduce capacity.

IT can create AVD pools with a custom image or an Azure default with Windows 10 multi-session. AVD pools also support Remote App streaming. This turns AVD into a PaaS to deliver apps to users over a secure network, making it a SaaS node.

Perhaps the biggest drawback for AVD is the complexity that comes with this flexibility -- a bit of a double-edged sword. There are, however, plenty of integrators ready to help from third parties, including the following:

The pay-as-you-go pricing model allows customers to pay for compute time rather than pay hourly. If a user runs that virtual desktop for 9 hours a day for 5 days, the customer would pay for 45 hours. If there is a 3-day holiday and the AVD is not in use, there is no charge, unlike the per-user model in Windows 365.

In addition, Microsoft offers a 'reserved instance' where a virtual desktop is reserved for dedicated use and paid for upfront for one year to three years. This can work well for customers with steady, predictable use patterns and can provide additional cost savings over standard pay as you go.

Another significant feature of AVD is that it allows customer management actions via the Azure portal, Azure Virtual Desktop PowerShell and REST interfaces. This enables IT to manage all OS versions and apps in one pane of glass.

The Azure Virtual Desktop requirements include the following:

At this point, organizations should ask which of these technologies is right for their business goals. However, the debate isn't simply Windows 365 vs. Azure Virtual Desktop -- maybe neither of these services would be a good fit. They may not be a good option for organizations that:

On the other hand, these two Microsoft services may be especially attractive for organizations that have:

Comparing different desktop virtualization services from Microsoft is an important topic for third-party virtualization vendors. One such example is Nerdio, an Azure and Windows virtual desktop integrator, which offers a helpful comparison calculator. Potential customers need to compare the cost models between AVD and Windows 365 to determine if a pay-as-you-go model will benefit their organization.

Some of the findings that Nerdio cites from this calculator include the following:

Nerdio also has a cost estimator to help determine the total cost of ownership of Azure.

In the past decade, on-premises Microsoft products such as Exchange server, SharePoint server, the Office productivity suite and file storage have transitioned to the cloud.

This shift proved to be a popular move among small businesses and enterprise organizations, many of which look for ways to take advantage of online platforms while reducing their data center footprint. Recently, Microsoft has promoted a new cloud service offering that provides its customers with a hosted version of its most popular product: the Windows operating system.

Using a public cloud to host a desktop session is not a new concept. Many enterprise organizations have taken advantage of Windows Terminal Services hosted within Azure and other competing platforms such as Citrix Cloud or Amazon Web Services to give users a hosted desktop experience. However, Windows 365 is built on Azure Virtual Desktop and aims to deliver a new experience to end users and IT system administrators. The Windows 365 Cloud PC product is an alternative to Remote Desktop Services with a different pricing structure and a new approach to management.

Cloud-hosted desktops offer value to organizations looking to reduce their dependency on physical hardware to deliver high-performance workstations. A virtual desktop hosted in Azure performs all its processing directly on Microsoft Azure servers.

In addition, Windows 365 brings the following benefits to organizations:

Microsoft also offers a discount of up to 16% of the monthly subscription of Windows 365 for customers with a valid Windows 10 or 11 Professional license. This only applies to those customers that are the primary users of the Windows 10 or 11 Pro licensed device. Microsoft's one requirement for its customers is that they must connect into the Windows 365 service from their licensed Windows 10 or 11 Pro device at least once during the setup process.

Microsoft offers two different plans as part of its Windows 365 subscription. First, the Windows 365 Business edition targets organizations with fewer than 300 users and Windows 365 Enterprise for any organization with more than that number. Of course, there could be exceptions to these situations. For example, a large organization may only want to subscribe to the Business edition for a select pool of users. The table in Figure 1 provides some additional details on what's included in each plan.

Figure 1.

Windows 365 offers a comprehensive set of features, and users can access their work machines from any device at any time. However, there are other factors that IT must take into consideration when planning a possible adoption of Windows 365 Cloud PC. This includes some of the following limitations or restrictions:

Note: Windows 365 Enterprise funnels Cloud PC network traffic through the Azure virtual network, and this pricing falls under the category of typical Azure bandwidth pricing.

Adopting VDI or Windows 365 offers customers a way to shift their end users' desktops to the client and the flexibility to centralize the management of those desktops. Virtual desktops combined with app deployment services integrate with Intune and Azure Active Directory (AD) to help assign different machine types to different users. This makes the management process efficient and easy. However, clients must ensure they understand the cost structure associated with the subscription and limitations or overages that may result from existing outbound data. Without this piece of the puzzle, the basic licensing costs wouldn't reflect the total cost of ownership of adopting this service.

App virtualization (application virtualization) is the separation of an installation of an application from the client computer that is accessing it.

Application containerization is an OS-level virtualization method used to deploy and run distributed applications without launching an entire virtual machine for each app.

Application layering (app layering) is a technology for delivering virtual applications that run in layers separate from a virtual desktop, but interact with the operating system and other apps as if they are installed natively on the base image.

Application sandboxing, also called application containerization, is an approach to software development and management and mobile application management (MAM) that limits the environments in which certain code can execute.

Application streaming is an on-demand software delivery model that takes advantage of the fact that most applications require only a small fraction of their total program code to run.

A set of virtual hardware devices, including virtual CPU, virtual RAM, virtual I/O devices, and other virtual hardware devices. It resembles and behaves like a traditional physical server and runs a traditional operating system (OS), such as Windows or Linux.

Many products and technologies today provide a platform on which VMs can be built and run. Although these technologies may have many fundamental differences, they tend to share these characteristics:

A VM running a server OS such as a Windows Server or a Red Hat Enterprise Linux Server. A virtual server typically runs one server-based application.

A VM that is running a desktop OS such as Windows 7 or Red Hat Enterprise Desktop. A virtual desktop typically has one direct, concurrent user.

A software component that resembles and behaves like a specific hardware device. The guest OS and software applications in the VM behave as though the virtual hardware device is actually a physical hardware device. A VM is a set of virtual hardware devices that correspond to the set of devices found in traditional physical servers, such as virtual CPUs, virtual RAM, virtual storage adapters, and virtual Ethernet adapters.

Software that resembles and behaves like a traditional Ethernet Adapter. It has a MAC address, and it receives and sends Ethernet packets.

Software that resembles and behaves like a traditional, physical CPU. Depending on the underlying technology, vCPUs could be software-emulated or software-modified:

Resembles and behaves like a physical disk. It may be a file, a set of files, software, or some other entity, but to a VM, it appears to be a SCSI disk. For example, in Microsoft Hyper-V, virtual disks are referred to as VHD files with the file extension vhd.

A virtual file system (VFS) is programming that forms an interface between an operating system's kernel and a more concrete file system.

A virtual machine (VM) is an operating system (OS) or application environment that is installed on software, which imitates dedicated hardware.

Virtual network computing (VNC) is a type of remote-control software that makes it possible to control another computer over a network connection.

A collection of VMs, virtual networks and storage, and other virtual items that can deploy and run business applications, as an alternative to running applications directly on physical infrastructure. It allows IT personnel to install software applications in traditional OSs, such as Windows and Linux, without needing to know details of the underlying physical infrastructure. The OSs and applications run in VMs, in virtual networks, and on virtual storage.

Virtual desktop infrastructure (VDI) is a desktop virtualization technology wherein a desktop operating system, typically Microsoft Windows, runs and is managed in a data center.

A complex system that provides a set of services to consumers, without requiring the consumer to understand any of the underlying complexities of the system. Although simple, this is a highly accepted definition of the term, even when used to describe non-IT clouds. For example, some people consider electricity, water, and cable television services to be provided by clouds.

Clouds provide some IT-based service, often utilizing virtual infrastructure. Businesses can use privately owned clouds, externally owned clouds, or both external and private clouds (hybrid clouds). Types of IT-based clouds include:

Private cloud is a type of cloud computing that delivers similar advantages to public cloud, including scalability and self-service, but through a proprietary architecture.

A thin OS designed solely to provide virtualization. It drives physical hardware, executes VMs, and dynamically shares the underlying hardware with the associated virtual hardware. It is not intended to serve directly as a general-purpose OS, instead, it provides the platform on which VMs can run.

The migration of a traditional server, such as a specific Windows 2008 sever, from physical server hardware to a VM.

Typically refers to the action of copying one VM or VM template to create a new VM. During a clone operation, the VM files are typically copied, renamed, and modified to customize the new VM.

A point-in-time capture of the state of a VM. Snapshots allow the user to revert the VM to a previously captured state. A primary use is to undo changes that were made in a VM but are no longer wanted.

The movement of VMs from one resource to another, such as from host to host or datastore to datastore.

A system or component that has some automatic protection in case of disruption. The protection may allow a small amount of unplanned downtime, but it will automatically correct the issue within a pre-determined time interval.

Ensures that a VM is automatically made available, although the host on which it runs fails. VM HA may require an automatic reboot of the VM on another host.

A virtual private network (VPN) is a service that creates a safe, encrypted online connection.

Desktop as a service (DaaS) is a cloud computing offering in which a third party hosts the back end of a virtual desktop infrastructure (VDI) deployment.

Software as a service (SaaS) is a software distribution model in which a third-party provider hosts applications and makes them available to customers over the Internet.

A measurement, usually in percentages, by which the amount of provisioned virtual hardware is greater than the actual physical resources. For example, if a set of thin-provisioned virtual disks is configured for a total of 3 TB, but the datastore where they reside is only 2 TB, then the over-commitment is 150 percent.

Refers to a state where the actual, attempted resource usage exceeds the capacity of the actual hardware resources. For example, if a set of VMs stored in the same datastore generate more I/O than the underlying LUN can accommodate, then the datastore is over-committed.

VMs executed directly on a client system, such as the user's PC. Some virtualization products, such as VMware Workstation and Microsoft Virtual PC, are designed solely for running local VMs. Some VDI products allow virtual desktops to run remotely in the datacenter, but also allow the user to check and execute the virtual desktop locally on client systems.

A client device that has a very lean implementation of Windows or Linux and is mainly intended to allow the user to connect to a remote virtual desktop rather than to run applications natively.

A client device that is even leaner than a thin client. Typically, a zero client runs an embedded, proprietary OS and has no local disk. It is used to connect to remote virtual desktops.

Also called a virtual machine monitor, a process that controls the execution of a VM and brokers its use of virtual hardware with the underlying host. It notifies the host when the VM needs to access the physical resources.

These features are commonly provided on modern CPUs, allowing the host to offload some of the virtualization work to the CPU to improve performance.

A packaged software application that runs in a virtualized, runtime environment, where the application perceives that it is natively installed. For example, a virtualized Windows-based application accesses a virtual Windows registry and virtual file system that are created at runtime by the runtime environment by overlaying modifications in the package on the native registry and file system.

A pre-built VM containing pre-installed software that can be easily implemented. Typically, the appliance is downloaded from a website as an OVF file, deployed into the virtual infrastructure, and easily configured using the console of the VM and a web browser. Most virtual appliances allow very simple implementation, relieving the customer of a complex installation and configuration.

PC over IP (PCoIP) is a remote display protocol that Teradici developed for delivering remote desktops and applications to endpoints.

Remote Desktop Services (RDS) is an umbrella term for several specific features of Microsoft Windows Server that allow users to remotely access graphical desktops and Windows applications.

A remote desktop is a program or an operating system feature that allows a user to connect to a computer in another location, see that computer's desktop and interact with it as if it were local.

A virtual desktop pool is a group of virtual desktops that are hosted on identically configured virtual machines.

GPU virtualisation is the next step up from CPU virtualisation and allows multiple 3D CAD users to share the resources of powerful individual GPUs.

GPU pass-through allows a physical GPU to be mapped directly to a virtual machine.

The workstation’s CPU resources are shared but each user has access to a dedicated graphics card.

A suite of products that provide reliable virtual infrastructure suitable for business-critical applications.

A feature of VMware vSphere that provides live VM migrations from host to host.

A feature in vSphere that provides automated resource control. Its main function is to provide automatic load-balancing based on CPU and RAM usage in a cluster of ESXi hosts by utilizing VMotion.

A feature in VMware vSphere that provides automated storage resource control. Its main function is to provide automatic balancing of disk space utilization within a cluster of datastores by utilizing Storage VMotion. It can also be used to automatically balance the I/Os in a cluster of datastores.

A feature of vSphere that provides automatic VM high availability against potential ESXi host failures. Whenever an ESXi host in a cluster fails, vSphere HA restarts the failed VMs on surviving ESXi hosts in the cluster.

A software application that should be installed in VMware-based VMs. It provides the latest virtual device drivers. It also runs paravirtualized services that communicate to the ESXi host to allow features such as time synchronization and heartbeats.

A file system designed to efficiently allow shared access from multiple ESXi servers, while supporting very large files. A VMFS datastore is a disk partition formatted with VMFS or a set of VMFS-formatted partitions (VMFS Extents) that are spanned to form a single VMFS. VMFS datastores are typically used to store VMs that run on VMware ESXi.

VMware ESXi, also called VMware ESXi Server, is a bare-metal hypervisor developed by VMware for vSphere

VMware Horizon Client is software that establishes a connection between endpoint devices and Horizon View virtual desktops and applications.

VMware Workspace ONE is a management platform that allows IT administrators to centrally control end users' mobile devices and cloud-hosted virtual desktops and applications from the cloud or from an on-premises deployment.

AWS (Amazon Web Services) is a comprehensive, evolving cloud computing  platform provided by Amazon that includes a mixture of infrastructure-as-a-service (IaaS), platform-as-a-service (PaaS) and packaged-software-as-a-service (SaaS) offerings. AWS services can offer an organization tools such as compute power, database storage and content delivery services.

Amazon Elastic Compute Cloud (Amazon EC2) is a web-based service that allows businesses to run application programs in the Amazon Web Services (AWS) public cloud.

An Amazon EC2 instance is a virtual server in Amazon's Elastic Compute Cloud (EC2) for running applications on the Amazon Web Services (AWS) infrastructure.

An Amazon Machine Image (AMI) is a master image for the creation of virtual servers -- known as EC2 instances -- in the Amazon Web Services (AWS) environment.

Amazon WorkSpaces Streaming Protocol (WSP) is a cloud-native streaming protocol that enables a consistent user experience when your end users are accessing their WorkSpaces across global distances and unreliable networks. WSP also enables additional features such as webcam support. As a cloud-native protocol, WSP delivers feature and performance enhancements without manual updates on your WorkSpaces.

A product that provides reliable virtual infrastructure suitable for business-critical applications. - based on the Xen Hypervisor

Allows multiple users to share a single desktop remotely.

A feature of Citrix XenServer that provides live VM migrations from host to host

A feature of Citrix XenServer that provides live VM migrations from datastore to datastore.

A software application that should be installed in XenServer-based VMs. It provides the latest virtual devices drivers.

Citrix HDX 3D Pro is a group of graphics acceleration technologies that help optimize the delivery of resource-intensive virtual applications on a company's XenDesktop and XenApp platforms.

Citrix Provisioning Services (Citrix PVS) is a software-streaming technology that allows administrators to patch or reconfigure an entire deployment of virtual desktops from one shared master image.

Citrix Receiver is a suite of products that allows client devices to connect to various desktop virtualization services offered by Citrix.

Citrix StoreFront is an enterprise application store that acts as a central location for users to access XenDesktop and XenApp virtual desktops and applications from their mobile devices, laptops, Windows PCs or Macs.

Citrix XenApp, now part of Citrix Virtual Apps and Desktops, was a product that extends Microsoft Remote Desktop Session Host (formerly known as Terminal Services) desktop sessions and applications to users through the Citrix HDX protocol.

Microsoft Hyper-V Manager is a tool that allows administrators to create, change and delete virtual machines (VMs).

A Microsoft Azure VM Scale Set is a group of individual virtual machines (VMs) within the Microsoft Azure public cloud that IT administrators can configure and manage as a single unit.

The new name for Office 365. a line of productivity applictions like Outlook, One Drive, Teams, Word, Excel, Powerpoint

Securely stream your Windows experience—including your personalized apps, content, and settings—from the Microsoft cloud to any device with your Windows 365 Cloud PC.

Azure Virtual Desktop is an Azure-based cloud service for desktop and application virtualization.

Windows Virtual Desktop Access (VDA) is an authorization strategy that requires each device seeking access to a virtual desktop in a Microsoft Virtual Desktop Infrastructure (VDI) to be licensed.