Storage DRS generates an alarm to indicate that it cannot operate on the datastore.

Storage DRS generates an event and an alarm and Storage DRS cannot operate.

The following scenarios can cause vCenter Server to disable Storage DRS for a datastore.

The datastore is shared across multiple datacenters.

Storage DRS is not supported on datastores that are shared across multiple datacenters. This configuration can occur when a host in one datacenter mounts a datastore in another datacenter, or when a host using the datastore is moved to a different datacenter. When a datastore is shared across multiple datacenters, Storage DRS I/O load balancing is disabled for the entire datastore cluster. However, Storage DRS space balancing remains active for all datastores in the datastore cluster that are not shared across datacenters.

The datastore is connected to an unsupported host.

Storage DRS is not supported on ESX/ESXi 4.1 and earlier hosts.

The datastore is connected to a host that is not running Storage I/O Control.

The datastore must be visible in only one datacenter. Move the hosts to the same datacenter or unmount the datastore from hosts that reside in other datacenters.

Ensure that all hosts associated with the datastore cluster are ESXi 5.0 or later.

Ensure that all hosts associated with the datastore cluster have Storage I/O Control enabled.