5.6.2.4 Hosts per Cluster
Determine the number of hosts for a cluster based on the following:
• Amount of available space on the vSAN datastore
• Number of available failures you wish to tolerate in the cluster
The number of hosts is generally a balance between hardware and space:
• More ESXi hosts and/or disk groups means higher hardware costs
• Fewer ESXi hosts and/or disk groups means resource availability could suffer
For instance, if the vSAN cluster has only three ESXi hosts, only a single failure is supported. If a higher level of availability is required, additional hosts are also required. For this reason, VMware recommends that the minimum production configuration include four hosts per cluster. However, a maximum of 64 is supported.