For VSI, we established that using analysis tools was a necessity, and VMware provided wonderful Capacity Planner tool. However, it soon became evident that for VDI, it is even more important to use analysis tools. That is because for VDI, when you buy hardware and software, the investment is generally higher. You need a lot more, faster storage. You need many servers and a fast network. So the margin of error is smaller.
Consequently, using Liquidware FIT or Lakeside SysTrack is essential. There are now a few more tools on the market, like ControlUp or Login PI. However, the new entrants have not been battle tested yet.
So how do you analyze your physical desktops for VDI?
First, buy a license for the Liquidware FIT tool (per user, inexpensive), or buy an engagement from your friendly Valued Added Reseller or Integrator who is a Liquidware partner. If you buy a service from a partner, then usually up to 250 desktop license will be included with the service.
Here, I will talk about services of the partner because that is what I do. However, if you are doing this yourself, just apply the same steps.
You will need to provide your partner’s engineer with space for 2 small Liquidware virtual appliances. The only gotcha is that you want them on the fastest storage you have (SSD preferable). That is because on slower storage, it takes much longer to process any analysis or reports.
The engineer will come and install the 2 appliances into your vSphere. Then, the engineer will give you an EXE or MSI with an agent. Usually, you can use the same mechanism you already use to install software on your desktops to distribute the agent. For example, distribution tools like Microsoft SCCM, Symantec Altiris, LANDesk, and even Microsoft Group Policy will all be good. If you don’t have a mechanism for software distribution, then your engineer can use a script to install the agents on all PCs.
Make sure to choose a subset of your PCs, and at least some from each possible group of similar users (Accounting, Sales, IT, etc.). Your sample size could be about 10-25% of total user count. Obviously, the higher the analysis percentage, the more accuracy you get. But the goal here is not 100% accuracy – it’s impossible to achieve 100%. Assessment and performance analysis is an art as much as a science. Thus, you need just enough users to get a ballpark estimate of what hardware you need to buy. Also, run the assessment for 1 month preferably, or at a bare minimum 2 weeks. The time of the start of the data collection above should start from the time you deploy your last user with the Liquidware agent.
Your partner engineer will need remote access, if possible, to check on the progress of the installation. First, the engineer will check if the agents are reporting successfully back to the Liquidware appliances. During the month, the engineer will make sure agents are reporting and data can be extracted from the appliance.
In the middle of the assessment, engineer will do a so-called “normalization” of the data. That is to make sure the results are compatible with rules of thumb for analysis. If necessary, the engineer will readjust thresholds and recalculate the data back to the beginning.
At the end of 30 days, the engineer will generate a machine-made report on the overall performance metrics, and will present the report to you.
At some partners, for an extra service price, the engineer will go further, and will analyze the report for the amount and performance parameters of hardware you need. In addition, the engineer will create a written report and present all the data to you.
In either case, you will know which desktops have the best score for virtualization, and which ones you should not virtualize. If you go with more advanced report services from your partner, then you will also understand how to map the results to hardware and further insights.
One way of mitigating bad VDI sizings is to also use a load simulation tool like LoginVSI. However, LoginVSI is only useful for clients who can afford to buy similar equipment for the lab that they will buy for production. Using LoginVSI, you can test robotic (fake) users doing tasks that normal users will do in VDI. LoginVSI allows you to have a ballpark hardware number that is good. However, the LoginVSI number does not have real user experience data. For that, you need tools like Liquidware FIT and associated work to determine proper VDI strategy.
Understanding what your current user experience is, and also how that experience could be accommodated with virtual desktops is essential to VDI. You should do this assessment before buying your hardware. Doing an assessment ensures that your users get the same experience or better on the virtual desktop as they have on the physical desktop (the holy grail of VDI).