Check out the man page for get-ncefficiency. That cmdlet is used for Netapp's overall efficiency.
The cmdlet returns a VolEfficiencyInfo object for each volume it investigaes. An EfficiencyInfo object contains the following values: - Capacity: The capacity of the storage object. - Used: The amount of space used on the storage object. - Free: The amount of space free on the storage object. - Returns: A ReturnsInfo object which describes the storage efficiency returns.
The VolEfficiency object returned contains the following volume-specific values: - SnapshotCount: The number of snapshots of the volume. - SnapshotReserve: The size of the snapshot reserve for the volume. - SnapshotUsed: The amount of space used by snapshots. - SnapshotOverflow: The amount of space consumed by snapshots outside of the snapshot reserve. - Reserve: The amount of space in the overwrite reserve. This space is saved as overwrite space for LUNs and files that have space reservation enabled. - ReserveUsed: The amount of reserve space that is currently in use. - SpaceReserve: The type of space reservation of the volume. This value can be: none, volume, or file. - QuotaCommitted: The total amount of space committed on the volume to tree quotas. - QuotaUsed: The amount of space used on the volume by qtrees with tree quotas set. - QuotaOvercommit: The amount of space overcommitted to tree quotas. If QuotaCommitted < Capacity then the quota overcommit is zero. - TotalLunSize: The total sze of all LUNs contained within this volume. - LunOverprovisionPercent: The LUN over-provisioning percent of the volume. This value is equal to (TotalLunSize / Capacity) * 100. - EffectiveUsed: The amount of space that would be used without NetApp storage efficiency technologies. This is equal to Used + Returns. - EfficiencyPercent: A percentage representing the overall storage efficiency of the volume. This is equal to (EffectiveUsed / Capacity) * 100. - Qtrees: A Hashtable containing the qtrees that exist for the volume."