Explanation/Reference:
Explanation : Storage I/O Control Requirements Storage
I/O Control has several requirements and limitations.
Datastores that are Storage I/O Control-enabled must be managed by a single vCenter Server system.

Storage I/O Control is supported on Fibre Channel-connected and iSCSI-connected storage. NFS

datastores and Raw Device Mapping (RDM) are not supported.
Storage I/O Control does not support datastores with multiple extents.

Before using Storage I/O Control on datastores that are backed by arrays with automated storage

tiering capabilities, check the VMware Storage/SAN Compatibility Guide to verify whether your automated tiered storage array has been certified to be compatible with Storage I/O Control.
Automated storage tiering is the ability of an array (or group of arrays) to migrate LUNs/volumes or parts of LUNs/volumes to different types of storage media (SSD, FC, SAS, SATA) based on user-set policies and current I/O patterns. No special certification is required for arrays that do not have these automatic migration/tiering features, including those that provide the ability to manually migrate data between different types of storage media.
Reference: http://www.vmware.com/pdf/vsphere4/r41/vsp_41_resource_mgmt.pdf