Persistent VDI Vs. Non-persistent VDI: Know the Differences

Ever since virtual desktop infrastructure (VDI) became a viable alternative to physical PCs in organizations, a raging debate about persistent VDI versus non-persistent VDI has ensued. With persistent VDI, users have their own desktops that run on specific virtual machines (VMs) in a datacenter.

In contrast, none of the users’ configurations or application data gets saved within the desktop when you implement non-persistent VDI. This article examines the differences and use cases for persistent and non-persistent VDI.

Key Differences Between Non-persistent and Persistent VDI

Persistent VDITo understand the major differences between persistent and non-persistent VDIs, it is vital to know how technology and the VDI market have evolved. Early adopters of virtual desktop infrastructure opted to virtualize desktops because it provided them with mobility, security and anywhere/anytime access benefits.

At the time, simply moving traditional PCs into the datacenters—which is what persistent VDI is about—was the fastest and most straightforward way to realize VDI benefits. Persistent VDIs are full-sized VM copies of traditional PCs. When specific users within the organization log in to VDI, they are assigned these full VMs.

Users can save files, change configurations and customize any setting at will on the VMs. The VMs are persistent because every time users log in, they access the same virtual machines. Persistent VDI are also called stateful VDI because customized data gets saved between user sessions.

While persistent desktops proved too quick to implement, they were challenging to manage and had high shared-storage costs. This prompted organizations to introduce the concept of non-persistent desktops, or stateless VDI. With non-persistent VDIs, desktops reside in pools. When a user logs in, a virtual machine gets pulled out from the pool and assigned to the user.

When the user is done with the desktop, the VM gets returned to the pool. At this time, all the changes made to the desktop get discarded—hence the term “non-persistent desktop”. Non-persistent VDI relies on a master image (also called a golden image or base image) to save IT administrators’ time and ensure consistency during the cloning process.

The master image contains the OS, configuration settings and other customizations that replicate to multiple virtual desktops. Each subsequent time you log in to the VM, you get a clean base image. Each virtualization company employs different technology when it comes to the cloning process.

For example, VMware leverages Linked Clones while Citrix uses Machine Creation Services (MCS) and Provisioning Services (PVS) to create and manage desktop images.

Non-persistent VDI: Pros and Cons

Below are the advantages and disadvantages of non-persistent VDI:

Pros Cons
Simplified management of desktops. Non-persistent desktops get built from the golden image. As such, IT administrators can patch and update the image easily, back it up quickly, and provision organization-wide applications to all the end users. Complex personalization. Since non-persistent desktops don’t use user profiles, it is difficult for users to personalize their desktops. While personalization is possible, the process requires the integration of third-party solutions that are costly and laborious. And because non-persistent VDIs don’t provide the same customizations and consistency, they are difficult to adapt.
Enhanced security. Since users cannot install or alter any configuration settings, these desktops are more secure than their persistent counterparts. If the golden image gets compromised or hacked, IT administrators can simply reboot the desktop to revert it to a clean state. Less flexibility in publishing applications. It is not easy to customize applications for different user categories because they share a common golden image. While IT administrators can create multiple golden images—one for each group or department—the process can get complicated for large-scale implementations of virtual desktops.
Less storage. Non-persistent desktops separate the OS—present in the golden image—from user configuration settings and data. This separation allows IT administrators to leverage other storage-based technologies such as block-based image sharing that stores data on a lower-cost device.

Persistent VDI: Pros and Cons

Below are the advantages and disadvantages of persistent VDI:

Pros Cons
Easy personalization and familiarity. Users can personalize persistent VDI easily because they can access their own files and shortcuts each time they start a session. This aspect of persistent VDI makes it easier to adapt because it provides the same customizations and consistency that traditional PCs offer. Storage challenges. All the individual, customized VMs require more storage capacity than a single master image does for non-persistent VDI. Due to these concerns, only organizations with large IT budgets and staff can deploy large-scale persistent desktops.
Fast deployment. It’s quicker and easier to deploy persistent desktops with migration techniques such as P2V conversions or cloning workplace images. Management challenges. Like traditional physical desktops, persistent desktops deteriorate over time as IT administrators and end users make changes to the logical drive and the Windows registry. As desktops continue deviating from each other, so does patching, and updates become complicated and costly.

Use Cases for Non-persistent and Persistent VDI

The decision about which option you should implement when it comes to persistent versus non-persistent VDI relies largely on the task you want to accomplish. Non-persistent VDI is the most appropriate model for environments that have simple application needs and require high availability.

One such environment is a call center having tens or hundreds of desktops that have the same set of applications and must be available to employees for a certain time in a day. Under these circumstances, non-persistent VDI can deliver the same applications for all the desktops via traditional application virtualization or application streaming technologies.

Besides call centers, other use cases for non-persistent desktops include:

Persistent VDI, on the other hand, is more appropriate for knowledge workers who need to install their own applications and access complex customized documents. Besides knowledge workers, persistent VDI is also more suitable for:

Parallels RAS Offers VDI Management

Delivering virtual desktops and applications on-demand to any device at any time is the primary reason why organizations undertake VDI or desktop virtualization projects. However, choosing a specific VDI solution can be a daunting task if you focus only on mobility and any device/anytime benefits.

Besides these obvious benefits, a great VDI solution should also simplify the end user experience and consolidate resources while allowing IT administrators full visibility into the technology stack. Parallels® Remote Application Server (RAS) is one such solution organizations can use to implement VDI effortlessly.

It doesn’t matter whether you’re deploying persistent or non-persistent desktops—Parallels RAS provides the flexibility you need to get started with the model of your choice quickly. By automatically deploying virtual desktops on-demand via customized templates, Parallels RAS allows IT administrators to provision guest VMs on the fly.

It also supports virtually all the major hypervisors, including VMware ESXi and Hyper-V, and hyper-converged infrastructures (HCIs) such as HPE, Scale Computing, and Nutanix Acropolis. Besides, Parallels RAS can also manage virtual desktops from different hypervisors under the same management console, offering the flexibility you need to implement VDI.

If your concern with VDI is security, Parallels RAS has got you covered. Parallels RAS leverages cutting-edge security protocols, including Federal Information Processing Standard (FIPS), Secure Sockets Layer (SSL), and Multi-Factor Authentication (MFA), among others, to secure corporate data from attacks.

Download your free 30-day Parallels RAS trial, and test-drive its VDI management capabilities!