By default, DRS works at the Fully Automated automation level. You can however, choose to set it to Manual or Partially Automated. Although the names of the automation levels are self-explanatory, there are a few additional differences.
Fully Automated: VM initial placement and migrations are done automatically
Partially Automated: VM initial placement is automatic, but migration recommendations are displayed to the administrator, and are not performed until the administrator applies them
Manual: Both initial placement and the migration recommendations are displayed to the administrator and requires the administrator's approval to be applied
The following procedure will help you modify the DRS automation level:
From the vCenter's inventory home, navigate to the Hosts and Clusters view.
Select the cluster and navigate to Manage | Settings | vSphere DRS and click on Edit.
On the Edit Cluster Settings page, click on DRS Automation to expand it and view...