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This content is part of the Essential Guide: How to set up VDI: Tips and considerations
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How to accurately assess your VDI hardware needs

Overestimating or underestimating hardware needs for a VDI deployment can cause major problems for IT. With a few simple pieces of advice, IT pros can get a more accurate picture.

When planning a VDI deployment, IT professionals must accurately determine their hardware requirements.

If IT pros overestimate the number of virtual desktops a host can run, they will end up with poor performance and likely find themselves asking management for money for additional VDI hardware. Conversely, if they overestimate the hardware requirements, they will end up wasting a lot of money on equipment they don't need. The key is finding a happy medium.

Be careful when following recommendations

When it comes to VDI hardware planning, IT pros should avoid the temptation to base their planning on the estimates they read online. Just because someone claims to be able to comfortably host 50 virtual desktops on hardware that is similar to what an IT pro plans to use does not necessarily mean that other organizations will have the same results. After all, one organization's users don't work with the exact same set of applications as another organization's users.

And, even if two organizations' users did work with identical applications, one set of users will be doing a different job from the users in the other company, which means their usage patterns will be unique.

Reading about another organization's experience with VDI hardware can give IT pros a rough idea of what to expect, but they shouldn't anticipate getting exactly the same results as someone else. Mileage will vary.

Look for any available predictive tools

Another step IT pros can take to ensure that they make reliable VDI hardware projections is to look for planning tools from VDI vendors. Some vendors, including Microsoft, offer calculators that can help IT determine exactly what hardware it will need.

Have you considered all your virtual desktop planning options?

IT has important decisions to make when choosing a VDI deployment, including whether to use persistent or nonpersistent desktops, what devices to give end users and more. Take this quiz and test your knowledge of the VDI planning process

The problem with VDI calculators is that IT pros cannot simply tell the calculator that they have 250 users and expect to get an accurate projection of the hardware they will need for their users with virtual desktops. Typically, they need to know how the users work with the hardware.

For instance, IT might need to know how many of those 250 users should be treated as power users and what the peak IOPS rate is for those users, as well as the duration for which they are at that peak. Similarly, IT pros might need to know the average amount of memory a typical knowledge worker consumes in their organization.

In any case, getting a good VDI hardware projection depends on providing the calculator with accurate information. If IT pros simply guess the values that the calculator asks for, then the calculator's projection will likely be inaccurate.

Small-scale testing

Another thing IT pros can do to get an accurate VDI hardware projection is to perform small-scale testing. Set up a few virtual desktops on unused hardware and ask a few users to try them out. At the same time, use performance monitoring tools to track the resources the virtual desktops consume.

Projecting VDI hardware requirements is always a bit tricky.

The users working from the virtual desktops can tell IT pros whether or not the test desktops perform well, while the performance monitoring data can tell them about resource consumption. IT pros can then use this information to fine-tune the virtual desktops and to create a projection that will tell them what hardware they'll need to ensure that users have a good experience.

Use what's already available

If IT lacks the resources to set up a pilot VDI deployment, it can get the information that it needs from users' existing physical desktops. Use a performance monitoring tool to track resource usage across several PCs. Remember that resource consumption is not uniform throughout the day, so it's best to log performance data for at least a week before analyzing it.

When the tests are complete, IT pros must remember that the data they've collected won't be an exact match for the resources a VDI deployment might consume. Even so, it should at least give them a reasonable idea of what to expect.

Projecting VDI hardware requirements is always a bit tricky. The key to making an accurate projection is having a solid understanding of usage patterns. Keep in mind, however, that these patterns change over time, so it is important to have some extra capacity available for the virtual desktops to use.

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What's the most challenging part of evaluating hardware needs for a VDI deployment?
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