If you have vSphere DRS configured and you actively use it, you must have one of the vSphere DRS migration thresholds configured. Below is a list of each available vSphere DRS migration threshold and what it means.
| Migration Threshold | Details |
| 1.00 | Apply only priority 1 recommendations. vCenter Server will only apply recommendations that must be taken to satisfy cluster constraints like affinity rules** and host maintenance. |
| 2.00 | Apply priority 1 and priority 2 recommendations. vCenter Server will apply recommendations that promise a significant improvement to the cluster’s load balance. |
| 3.00* | Apply priority 1, priority 2, and priority 3 recommendations. vCenter Server will apply recommendations that promise at least good improvements to the cluster’s load balance. |
| 4.00 | Apply priority 1, priority 2, priority 3, and priority 4 recommendations. vCenter Server will apply recommendations that promise even a moderate improvement to the cluster’s load balance. |
| 5.00 | Apply priority 1, priority 2, priority 3, priority 4, and priority 5 recommendations. vCenter Server will apply recommendations that promise even a slight improvement to the cluster’s load balance. |
* default setting
** There are two types of Affinity Rules, VM-VM Affinity Rules and VM-Host Affinity Rules. VM-VM Affinity Rules, allows you to specify whether certain VMs should be placed on the same host or if this should be avoided. VM-Host Affinity Rules specify whether a members of a VM DRS group can run on a Host DRS group.