A data storage management approach is disclosed that performs backup operations flexibly, based on a dynamic scheme of monitoring block changes occurring in production data. The illustrative system monitors block changes based on certain block-change thresholds and triggers block-level backups of the changed blocks when a threshold is passed. Block changes may be monitored in reference to particular files based on a reverse lookup mechanism. The illustrative system also collects and stores historical information on block changes, which may be used for reporting and predictive analysis.