For many organizations the benefits of virtualizing user desktop systems is hard to ignore – improved data protection, enhanced data security and the opportunity to drive improved resource and operational efficiencies. The challenge is unless the virtual desktop experience is nearly identical to physical desktop platforms, users will be much less apt to accept them. For this reason, the storage that is allocated in VDI implementations will be a critically important element towards ensuring consistent user experience and ultimately, the success of the VDI project itself.
To Persist or Non-Persist
There are two ways to deploy VDI – persistent desktops or non-persistent desktops. Non-persistent desktops offer a way to fully exploit the efficiency and manageability benefits of VDI but are sometimes considered a riskier alternative than their persistent desktop counterparts. As the name implies, non-persistence refers to the state by which resources are allocated to virtual desktops. In short, resources are served up on an “on demand” basis rather than in a dedicated fashion.
On the other hand, persistent desktops are designed to be “always on”; enabling users to immediately login to their workstations and have a full compliment of dedicated resources allocated for their individual use. In addition, existing physical desktop management tools can be used in persistent desktop environments; making the transition to VDI much more straightforward from an initial operational perspective.
The challenge is that persistent desktops require significantly more VDI host memory and shared storage resources than their non-persistent counterparts and hence more cost. Even when only 50% of persistent desktops are in use, the VDI environment must maintain a hard allocation of all the storage (unless aided by other technology), CPU and server memory resources as though 100% of the users were signed in.
New Management Realities
Furthermore, the perceived benefit of repurposing physical desktop management tools with persistent desktops may actually turn out to be a liability. Application upgrades, for instance, can be pushed out to physical desktops quite easily since these systems have their own discrete CPU and storage I/O resources to process the installation. However, when application upgrades are processed on a single LUN servicing hundreds or thousands of persistent desktops, the shared storage environment could be brought to its knees. For these reasons, scheduled upgrades have to be very carefully managed in persistent environments.
A universal concern about the deployment of VDI infrastructure is that desktop quality of service (QoS) can be easily compromised; whether in persistent or non-persistent environments. One example is a “rogue” virtual desktop (also known as a “noisy neighbor) that unexpectedly begins monopolizing storage I/O resources at the expense of all the other VDI users, resulting in excruciatingly slow performance.
Software Enabled VDI
In recent years, new storage technologies have come to market that are designed to specifically address the I/O performance issues that are typically present in virtualized server and desktop infrastructure. Server-side SSD storage along with storage arrays that either exclusively use all flash capacity or a hybrid mix of SSD and spinning disk, provide a variety of high performance options. While these offerings can go a long way towards ensuring good VDI performance, they can be quite expensive, particularly in a persistent environment and often can upend the ROI of the VDI project.
Lower cost commodity disk, on the other hand, cannot manage the highly random, high volume I/O workloads that are characteristic of VDI infrastructure. To keep costs in check and to ensure a reliable, quality user desktop experience, VDI storage planners would be well served by first performing a full assessment of their environment prior to making any storage purchases. Only after gathering all the relevant details about their desktop users unique requirements, can a non-persistent deployment be accurately designed and implemented.
Armed with this information, storage planners can deploy a solution which strikes the right balance between high performance storage and lower cost disk capacity. Furthermore, when utilizing VDI software tools like those from Liquidware Labs, virtual desktop storage planners can granularly assign storage IOPs to virtual desktops to ensure that noisy neighbors conditions will never manifest themselves in their environments. Lastly, these tools also enable virtual desktop users to customize their environments through the use of centrally administered “roaming profiles” and “follow me data disks”. The net effect is that users experience a consistently good virtual desktop performance while maintaining a personalized “look and feel”.
To learn more on how to successfully implement non-persistent desktops in your environment, please go the following on-demand version of a recently held webinar between Storage Switzerland and Liquidware Labs….CLICK HERE TO WATCH ON DEMAND