VM Sizing Calculator for Home Labs

A virtual machine sizing calculator are a tool that will allow you to determine the correct size for the virtual machine in your home lab. When sizing virtual machines, many people focuses on CPU or memory values for their virtual machines. However, these individual tend to fail to account for how the resource within their home lab interact with each other.

A virtual machine sizing calculator will help you determine the interaction between the resource in your home lab. Therefore, by using the calculator to plan your hardware purchase for your home lab, you can avoid buying hardware that will either underperform or leave resource within your hardware unused. To create the virtual machine sizing calculator, several value must be entered into the calculator.

Plan Your Home Lab with a Virtual Machine Sizing Calculator

These values relate to the virtual machines that will run within the home lab. You must enter the number of virtual machines you plan to use, the vCPU value of each virtual machine, and the CPU utilization that the virtual machines will require into the virtual machine sizing calculator. In addition to these values, you must enter the amount of RAM that you would like to assign to each of your virtual machine and the percentage of that RAM that you will commit to those virtual machines.

These values are required because you are likely to reach the memory limit of your hardware before you reach the CPU limits. Finally, you must also enter the type of storage and the IOPS (input/output operations per second) value that your virtual machines will require. For instance, the virtual machines that you create to perform media workload will require different IOPS values than a set of virtual machines dedicated to housing databases.

The virtual machine sizing calculator will output several value for the user. Based on the ratio of resources that are configured into your virtual machines, the virtual machine sizing calculator can determine the number of host for your virtual machines. It can also calculate the safe density of virtual machines for each of your host.

The safe density value will allow you to determine if your hardware is able to absorb more virtual machine, or if it has reach the limit for that specific resource. In addition, the virtual machine sizing calculator will display a breakdown of the amount of pressure that your virtual machines will place on each of the resource within your home lab. The resource that receive the most pressure will be of most interest to you as the administrator.

The virtual machine sizing calculator also contain reference table that feature workload profile multiplier. These workload profile multipliers allow you to adjust the expectation for your virtual machines for specific task. For instance, a media transcode workload will require a higher CPU multiplier than a backup repository, but the backup repository will require a higher network or storage write multiplier.

These values can be used to change the number of host required for your virtual machines. This adjustment process is much easier than adjust each of the virtual machines individually. You can use the virtual machine sizing calculator to determine the overcommit ratio of each of your resource.

The virtual machine sizing calculator allows you to test different CPU overcommit ratio. Many individuals use a four to one CPU overcommit ratio for their virtual machines since the virtual machines will be idle most of the time. However, you will not want to use such a ratio for RAM unless all of the virtual machines are dormant.

The virtual machine sizing calculator allows you to test both conservative and aggressive overcommit setting for each of your resource. This allows you to see how many host you will require should you deviate from your current overcommit setting for your virtual machines. Despite the virtual machine sizing calculators many feature, there are a few constraint to your home lab that the virtual machine sizing calculator cannot account for.

Some of these constraint may include the power draw that your server create, the cooling requirement for your home lab, and the noise that certain server will generate. The topology of the network in your lab may be another constraint that is not account for in the virtual machine sizing calculator. Although your network topology may support your average amount of data transfer, it may become saturated with a specific amount of data transferred at once, such as during a backup.

The placement of virtual machines within each host may also be a constraint that the virtual machine sizing calculator does not account for. If a virtual machine is not properly place within the host that you assign it to, you may lose that host. In addition to the feature discussed above, the virtual machine sizing calculator also feature reference table that include common virtual machine starting point.

These reference table will assist you should you find yourself unsure of the specification for your virtual machines. These virtual machine sizing calculator reference table are not to be copied directly from the calculator to your home lab. However, they will assist you in calibrating your expectation for the resource that each type of virtual machine will require.

For instance, a pfSense router virtual machine will not require a lot of storage or IOPS. However, a Windows development desktop may require more memory and IOPS for its virtual machines to allow the desktop for development work to start up quick. The virtual machine sizing calculator is the tool that will handle all of the mathematical calculation for your home lab.

The virtual machine sizing calculator will eliminate the need to have separate spreadsheet for CPU, memory, and storage resource within your lab. However, the virtual machine sizing calculator will not account for your personal judgment on how many host and resource you need for your home lab. Should your home lab be used only for learning, you can likely purchase low headroom for your virtual machines.

For other task that your household depends upon, you will need to purchase more headroom within each host for the virtual machines that provide those task. Headroom can be adjusted in the virtual machine sizing calculator so that you can see how many additional host you may require should you increase the headroom for each of your virtual machine. When you begin to plan for your future hardware purchase for your home lab, the virtual machine sizing calculator will change the way that you plan.

Instead of purchasing the most powerful host available in your price range, you can use the virtual machine sizing calculator to determine if two less powerful host would provide a better return in relation to the virtual machines that will be added to each host. Using such an application before purchasing hardware for your home lab will save you money. The virtual machine sizing calculators true value lies in its ability to allow you to view how one variable within your home lab can affect another.

By adjusting one variable at a time, you can determine what resource will become the limiting factor to your lab. You can also use the sizing calculator to determine if that limiting factor is based off the actual resource requirement for each virtual machine, or if it is based upon an overly conservative estimation of those requirement. By using this virtual machine sizing calculator for a few iteration for your home lab, you will have a better understanding of your home lab and be able to make a better decision about your future hardware purchase.