Filesystems are generally backed up incrementally to minimize the backupwindow and to optimize storage space.
文件系统通常为递增备份，这是为了最小化备份窗口和优化存储空间。
2
It decreases the backupwindow, ensures the data security and consistency, meets the needs of data backup at low cost.
缩短备份窗口，保证备份速度及数据安全性，降低备份成本。
3
Study the control of backup granularity and demarcation criterion, and divide backup data to satisfy the system requirement according to backupwindow and system stability.