Space Reclaimer is a SnapDrive for Windows feature that optimizes LUN space by marking newly freed space that is visible to NTFS so that it is also seen as available by Data ONTAP. Using Space Reclaimer lessens the disparity in available space that is reported by the two systems.
When files are deleted or modified on a LUN, the space is tracked by NTFS, but since this information is not communicated to the Data ONTAP file system, a disparity can grow between the available space reported by a SnapDrive host and a storage system. Space Reclaimer ensures that newly freed blocks are marked as available on the storage system.
You can use Space Reclaimer on traditional LUNs and on VMDK files attached as virtual disks using NFS datastores.