vSphere Storage Distributed Resource Scheduler (Storage DRS or SDRS) is a unique feature that continuously balances storage space usage and storage I/O load, avoiding resource bottlenecks to meet service levels and increase manageability of storage at scale.

Storage DRS provides initial placement and on-going balancing recommendations for datastores in a Storage DRS-enabled datastore cluster. A datastore cluster represents an aggregation of datastore resources, analogous to clusters and hosts.

vCloud Director 5.1 supports Storage DRS when using vSphere 5.1 hosts. Storage DRS also supports fast provisioning (linked clones) in vCloud Director 5.1.

vCloud Director 5.1 recognizes storage clusters. The member datastore clusters are visible in vCloud Director, but cannot be modified from vCloud Director.

Storage DRS is leveraged for initial placement.

vCloud Director uses Storage DRS to manage space utilization and I/O load balancing. Storage DRS is leveraged for rebalancing of virtual machines, media, and virtual machine disks within the storage pod.

As in vCloud Director 1.x, vCloud Director 5.1 decides on optimal placement between datastore clusters and standalone datastores across all vSphere instances assigned within vCloud Director.

There is a new VIM object type in the REST API named DATASTORE_CLUSTER. The datastore properties now include the member datastore list when the VIM object type is DATASTORE_CLUSTER.