You can create a VMDK anti-affinity rule for a virtual machine that indicates which of its virtual disks must be kept on different datastores.

VMDK anti-affinity rules apply to the virtual machine for which the rule is defined, not to all virtual machines. The rule is expressed as a list of virtual disks that are to be separated from one another.

If you attempt to set an intra-VM anti-affinity rule and an intra-VM affinity rule for a virtual machine, vCenter Server rejects the most recently defined rule.

If a virtual machine is subject to a VMDK anti-affinity rule, the following behavior applies:

Storage DRS places the virtual machine's virtual disks according to the rule.

Storage DRS migrates the virtual disks using vMotion according to the rule, even if the migration is for a mandatory reason such as putting a datastore in maintenance mode.

If the virtual machine's virtual disk violates the rule, Storage DRS makes migration recommendations to correct the error or reports the violation as a fault if it cannot make a recommendation that will correct the error.

No intra-VM anti-affinity rules are defined by default.


Browse to the datastore cluster in the vSphere Web Client navigator.


Click the Manage tab and click Settings.


Under Configuration, select Rules.


Click Add.


Type a name for the rule.


From the Type menu, select VMDK anti-affinity.


Click Add.


Click Select Virtual Machine.


Select a virtual machine and click OK.


Select at least two virtual disks to which the rule applies and click OK.


Click OK to save the rule.