Set DRS automation level
You can determine whether DRS will just display migration recommendations or automatically perform the migration when the cluster becomes unbalanced by defining the automation level. DRS makes these decisions on VM placement when a VM is powered on and when VMs must be rebalanced across hosts in the DRS clusters. Three automation levels are available:
- Manual – when a virtual machine is powered on, DRS will display a list of recommended hosts on which you can place the VM. If the DRS cluster becomes unbalanced, DRS will display recommendations for VM migration.
- Partially Automated – when a VM is powered on, DRS will place it on the best-suited host, without prompting the user. If the DRS cluster becomes unbalanced, DRS will display recommendations for VM migration.
- Fully Automated – when a VM is powered on, DRS will place it on the best-suited host, without prompting the user. If the DRS cluster becomes unbalanced, DRS will automatically migrate VMs from overutilized hosts to underutilized hosts.
The Migration Threshold slider bar determines how aggressively DRS select to migrate VMs. For the Fully Automated level, five options are available:
- Level 1 (Conservative) – apply only priority 1 recommendations. vCenter Server applies only recommendations that must be taken to satisfy cluster constraints like affinity rules and host maintenance.
- Level 2 – apply priority 1 and priority 2 recommendations. vCenter Server applies recommendations that promise a significant improvement to the cluster’s load balance.
- Level 3 – apply priority 1, priority 2, and priority 3 recommendations. vCenter Server applies recommendations that promise at least good improvement to the cluster’s load balance. This is the default value.
- Level 4 – apply priority 1, priority 2, priority 3, and priority 4 recommendations. vCenter Server applies recommendations that promise even a moderate improvement to the cluster’s load balance.
- Level 5 (Aggressive) – apply all recommendations. vCenter Server applies recommendations that promise even a slight improvement to the cluster’s load balance.
