Storage DRS collects resource usage information for all datastores in a datastore cluster. Storage DRS uses the information to generate recommendations for virtual machine disk placement on datastores in a datastore cluster.

Storage DRS recommendations appear on the Storage DRS tab in the vSphere Client datastore view. Recommendations also appear when you attempt to put a datastore into Storage DRS maintenance mode. When you apply Storage DRS recommendations, vCenter Server uses Storage vMotion to migrate virtual machine disks to other datastores in the datastore cluster to balance the resources.

You can apply a subset of the recommendations by selecting the Override Suggested DRS Recommendations check box and selecting each recommendation to apply.

Table 1. Storage DRS Recommendations
Label Description
Priority Priority level (1-5) of the recommendation. (Hidden by default.)
Recommendation Action being recommended by Storage DRS.
Reason Why the action is needed.
Space Utilization % Before (source) and (destination) Percentage of space used on the source and destination datastores before migration.
Space Utilization % After (source) and (destination) Percentage of space used on the source and destination datastores after migration.
I/O Latency Before (source) Value of I/O latency on the source datastore before migration.
I/O Latency Before (destination) Value of I/O latency on the destination datastore before migration.