Sizing is always done based on VMware KB article 2146615. Always validate any new deployment against the latest sizing guidelines provided online.

The KB article also provides for a sizing Excel document (advanced tabs) to be used for any sizing. Because the sizing document does not provide for sizing data for all adapters, additional data must be included in the Other Data Sources area of the Excel document. The amount of objects/metrics can be collected from within vRealize Operations Manager.

Because the service provider environment is used to host access for external users, the sizing based on actual system access must be considered as well: The maximum number of concurrent users is achieved on a system configured with the objects and metrics at 50 percent of supported maximums. (For example, 4 large nodes with 20K objects or 7 nodes medium nodes with 17.5K objects.) When the cluster is running with the nodes filled with objects or metrics at maximum levels, the maximum number of concurrent users is 4 users per node. (For example, 16 nodes with 120K objects can support 64 concurrent users.)

Any configuration operating in high availability mode must account for twice the number of nodes. This will not change the maximum amount of 16 nodes.

See the following snapshot for the base figures.