The best practice for the resource sizing effort of the Cloud Foundation domains is to consider initial baseline of resources required for overall management based on use cases, and then calculate the additional resources needed for guest virtual machines.

Dell Technologies uses a sizing tool to calculate the workload resource requirements for the Cloud Foundation domains. Dell Technologies will conduct a sizing exercise to determine the pools of resources required to satisfy VI workload domain demands and their service level objectives at an optimal cost.

Figure 29.    VxRail online sizing tool

The VxRail sizing tool performs calculations on one Cloud Foundation domain at a time. Therefore, the resources overhead required for management of each of the VI workload domains can be factored into the sizing effort for the management workload domain.

Figure 30.    Selecting options for architecture in VxRail sizing tool

At least one workload domain is also included in the sizing effort. It is important to understand the applications planned for each respective workload domain to ensure accurate sizing.

Figure 31.    Sizing VI workload domain in VxRail sizing tool

For calculating resource requirements for guest virtual machines, the VxRail sizing tool accepts sizing data either through manual entry or by downloading metrics from a collector tool. For the most accurate sizing calculations, Dell Technologies’ best practice is to use a collector tool for guest virtual machine resource requirements. Dell Technologies uses LiveOptics data collection for this purpose. The capture from the data collector can then be input directly into the VxRail sizing tool to produce the sizing report for each VxRail cluster.

Figure 32.    LiveOptics main dashboard

The VxRail sizing tool also supports reference workloads. A reference workload is a synthetic workload that attempts to represent real-life workloads. Select the reference workloads that best represent what is planned for a given VI workload domain to enable proper sizing.

The VxRail sizing tool performs its calculations using virtual machine profiles, and number of virtual machines that fit for each profile. Note that more than one profile can be defined for the same sizing exercise.

For best results, define the following metrics for each virtual machine profile:

• A reference workload
• The expected I/O activity per VM
• The usable storage capacity per VM
• The number of vCPUs or the amount of CPU in MHz per VM
• The amount of memory per VM

Dell Technologies will include the sizing metrics entered for each virtual infrastructure domain, and then perform the sizing analysis. When the settings are finalized, the resulting report from the VxRail sizing tool will show the required node count for a VxRail model and the HW characteristics for each node to meet the overall workload requirements.