Situations when you may want to exclude hosts from recommendations include when:
- You want to run the pool in Maximum Density mode and consolidate and shut down hosts, but there are specific hosts you want to exclude from this behavior.
- When two virtual-machine workloads always need to run on the same host (for example, if they have complementary applications or workloads).
- You have workloads that you do not want moved (for example, domain controllers or SQL Server).
- You want to perform maintenance on a host and you do not want virtual machines placed on the host.
- The performance of the workload is so critical that the cost of dedicated hardware is irrelevant.
- Specific hosts are running high-priority workloads (virtual machines), and you do not want to use the High Availability feature to prioritize these virtual machines.
- The hardware in the host is not the optimum for the other workloads in the pool.
Regardless of whether you specify a fixed or scheduled optimization mode, hosts excluded remain excluded even when the optimization mode changes. Therefore, if you only want to prevent Workload Balancing from powering down a host automatically, consider not enabling (or deselecting) Power Management for that host instead as described in Optimizing and Managing Power Automatically.