Use this report to determine how much storage space you would need to back up data that has been modified in the last day, week, month, two months, three months, six months, nine months, or year.
For example, if you want to back up the files that have been modified in the last 3 months only, generate this report and view the values in the "Last Modified <= 3 months" column to determine how 1) many files changed and 2) how much storage those changed files are consuming.
This report can be generated by Directory, by Directory Group, by Filesystem, by Filesystem Group, by Cluster, by Computer, by Computer Group, by Domain and Network Wide. This allows you to see for any of these levels, how much data would need to be backed up for any of these desired time intervals. This is useful for backup sizing and can be used to determine appropriate backup groups and sets for timing your backups.
For more information, see Backup Reporting - Backup Storage Requirements Overview.