The Commvault software uses the Dell EMC Isilon/PowerScale Changelist API for faster incremental backups.
When you have a large number of files to back up in a data set, even if only a few files were modified, regular file system incremental backups scan all the files to check for changes, which takes a large amount of time.
Changelist tracks the changes made to files between snapshots. When you run an incremental backup, only the files that changed are scanned, so the backup is faster.
Dell EMC Isilon/PowerScale OneFS version 126.96.36.199 and more recent versions.