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 VMDK 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 VMDK anti-affinity rules are defined by default.
- Browse to the datastore cluster in the vSphere Client.
- Click the Configure tab and click Configuration.
- Select VM/Host 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.