About reclaiming blocks on a LUN

To optimize Snapshot copy space usage, SnapDrive for Windows provides a feature called Space Reclaimer that enables you to mark newly freed blocks as available on the storage system when files are deleted from a LUN.

As blocks are deleted, NTFS keeps track of the freed space, but since this information is not communicated to WAFL, a disparity can grow between the available space reported by a SnapDrive host and a storage system. For optimum storage performance, you should run the Space Reclaimer as often as possible and until the entire NTFS file system has been scanned, but the process is CPU intensive and can take a long time to complete, so it must be balanced with other server activities.

Keep these recommendations in mind when using Space Reclaimer:

Do not run disk defragmentation at the same time Space Reclaimer is running. Doing so can slow the disk reclamation process.
Run Space Reclaimer when system usage is low; for instance, at night.

Space Reclaimer currently has the following limitations:

In MSCS configurations, it can be initiated from the owner node only.
It reclaims nearly all space from newly freed blocks, but not 100 percent of the space.

Reasons for SnapDrive to automatically stop space reclamation
SnapDrive for Windows automatically stops Space Reclaimer in several instances.
Starting space reclamation
Complete these steps to start SnapDrive for Windows space reclamation using the Computer Management panel.
Stopping space reclamation
Complete these steps to stop SnapDrive for Windows space reclamation using the Computer Management panel.

Parent topic: Managing LUNs