PowerScale OneFS 9.7.0.0 Backup and Recovery Guide

Commvault sparse file support: data aging and space reclamation

You can add support for file sparsing through SMB, specific to Commvault backup workflows.

The Commvault backup application interfaces with OneFS over SMB protocol. The Commvault application stores all data that must be backed up in large, indexed files. When data ages past a retention policy, if Commvault cannot delete the entire file, it attempts to free up sections of the tarball by converting them to sparse blocks. These tarball files can be large (more than 3 GB), and the range of hole punch arguments can also be large. To accomplish this, Commvault sends an FSCTL SET ZERO DATA call over SMB. This request comes with a range, and the expectation is that the server must convert the specified range to sparse blocks, freeing up space. This feature is provided in addition to the existing support for space savings from the delete and truncate operations on backup container files.

Capacity utilization with sparse file savings is best viewed with the du -sh command on the PowerScale cluster. The file and folder properties from Microsoft Windows represents the savings from delete and truncate operations but may not represent the sparse file savings.