What are IOPS, and how do they affect virtual desktop performance?

This week, our experts explain why input/output operations per second, or IOPS, matter when measuring virtual desktop performance.

How should I manage the end-user virtual desktop experience? What do IOPS have to do with it?

As with every other facet of IT infrastructure, performance of virtual desktop environments always comes under scrutiny if and when end users report that their virtual machine experience is lacking. This raises some interesting questions. First, how you measure virtual desktop infrastructure (VDI) performance? Once you determine what metrics you'll use, what should you do with the VDI performance information you glean from such measurements?

Ins and outs of IOPS

Input/output per second (IOPS) is a traditional measure of VDI performance. As the distance between the user's location and the physical hardware that runs a virtual machine (VM) increases, our measures of performance shift from local hardware metrics (such as disk read/writes, CPU utilization and memory paging) to how many times per second a virtual desktop talks or and listens to the infrastructure. That's what IOPS counts.

It's an important metric, but there is more to measuring virtual desktop performance than IOPS.

The IOPS cyclops

IOPS, just like the mythical Cyclops, has only a limited view of VDI performance. Have you ever gotten end-user complaints about an application's performance, only to get measurements showing that the servers and networks were operating normally when you checked monitoring tools and ran server and network performance benchmarks?

Although IOPS is a valid tool for monitoring performance and for tuning a VDI infrastructure, end-user perceptions of virtual desktop performance remain the gold standard.

The need for speed

The primary way to check on VDI performance occurs when a user moves the mouse across a virtual screen, opens Microsoft Word or submits a database query through a VM. If any of these actions complete too slowly, users get frustrated and start to complain. Many companies inadvertently deploy phone-based performance monitoring of their VDI environments by waiting for the help desk to tell the IT staff when they hear about performance problems.

Instead, be proactive: Use IOPS to tune VDI internals, but find a way to measure the user experience with VMs as well. End-user perspective-monitoring tools have been around for many years. Use them wisely and often, and do whatever you must to improve the end-user experience, and your users -- and managers -- will thank you.

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