Sizing considerations

This section provides various general best practices for sizing your deployment.

• User density—If concurrency is a concern, calculate how many users will use the environment at the peak of utilization. The option is also available to power off the AI VMs and bring up additional VDI VMs to support the user workload as required.
• Disaster recovery—For DR planning, implement a dual or multi-site solution, as recommended by Dell Technologies. The goal is to keep the environment online and, in case of an outage, to perform an environment recovery with minimum disruption to the business.
• Management and compute clusters—Dell Technologies recommends that you separate the management and compute layers into separate clusters. You can use a combined management and compute cluster for small environments. Consider using the PowerEdge R650 platform to reduce data center footprint when creating a management cluster for a large-scale deployment. With larger storage and graphics capabilities, Dell Technologies recommends R750 for compute clusters.
• Network isolation—When designing for larger-scale deployments, consider physically separating the management and VDI traffic from the vSAN traffic for traffic isolation and to improve network performance and scalability. This design illustrates a two-NIC configuration per appliance with all the traffic separated logically using VLANs.
• FTT—Dell Technologies recommends sizing storage with NumberOfFailuresToTolerate (FTT) set to 1, which means that you must double the amount of total storage to accommodate the mirroring of each VMDK.
• Slack space—Dell Technologies also recommends adding an additional 30 percent of slack space to prevent automatic rebalancing of storage, which impacts performance. Automatic balancing occurs when the storage reaches 80 percent of the full threshold. Therefore, 70 percent is recommended to reserve a 10 percent buffer.
• All-Flash compared with hybrid:
  • Hybrid and all-flash configurations have similar performance results. Because hybrid uses spinning drives, consider the durability of the disks.
  • Only all-flash configurations offer deduplication and compression for vSAN. Dell Technologies recommends all-flash configurations for simplified data management.
  • All-flash configurations need considerably less storage capacity than hybrid configurations to produce similar FTT, as shown in the following table: