In the context of Virtual Volumes replication, fault domains define how specific replication groups must be combined when being replicated from a source to a target site.

Fault domains are configured and reported by the storage array, and are not exposed in the vSphere Web Client. The Storage Policy Based Management (SPBM) mechanism discovers fault domains and uses them for validation purposes during virtual machine creation.

For example, provision a VM with two disks, one associated with replication group Anaheim:B, the second associated with replication group Anaheim:C. SPBM validates the provisioning because both disks are replicated to the same target fault domains.

Now provision a VM with two disks, one associated with replication group Anaheim:B, the second associated with replication group Anaheim:D. This configuration is invalid. Both replication groups replicate to the New-York fault domain, however, only one replicates to the Boulder fault domain.