VxRail scale-out clusters start with as few as 2 nodes and can grow in 1-node increments up to 64 nodes, providing performance and capacity to meet a wide range of use cases. New systems can be added nondisruptively, and different models can be mixed within a VxRail cluster. Flexible storage options also allow a node to start with a few drives, and drives can be added as capacity requirements grow, as shown in the following figure. Single-node upgrades and drive scalability protect an optimized initial investment. Customers can start with what they need and expand the VxRail cluster by adding nodes or drives, or both, to increase performance and capacity as needed. 

Figure 22.    VxRail scale on demand

For planning, consider these basic rules about scaling:

Balance

• At initial deployment, the first three nodes in a cluster must have identical configuration. A 2-node vSAN cluster requires both nodes to be identical.
• All nodes must be running the same version of software.
• Hybrid and all-flash or all-NVMe nodes cannot be mixed in the same cluster.
• 10 GbE and 25 GbE base networking cannot be mixed in the same cluster. 
• VMware requires that all nodes in a cluster are from the same processor vendor, either Intel or AMD. A cluster may have different generations of processors from the vendor.

Flexibility

• Systems in a cluster can be different models or series after initial deployment.
• A cluster can have a varied number of drives, CPU, memory, and model types.
• A cluster can have from 2 to 64 nodes

Upgradeable options

With VxRail, customers can upgrade nodes or add memory, NIC cards, cache drives, and capacity drives. GPUs and SmartDPUs can be upgraded or added in the supported node types. It is not possible to upgrade from all-flash to all-NVMe.