Changed Block Tracking for Image-Based Backups
Changed Block Tracking is an algorithm that features a decrease in source data reading on incremental image-based backups.
The Changed block tracking algorithm is supported by NTFS file systems only
This functionality is not supported for legacy backup format
How It Works
Once a first full backup is made, each MFT (Master File Table) is marked. On subsequent incremental backup runs, MFT is read again and blocks are compared. If a block is modified, a modified block tracking algorithm mechanism determines which files have been modified and locates disk clusters that contain file data.
Once all blocks are compared, only modified blocks are sent for reading.
As a result, the changed block tracking algorithm reduces the processed data amount when reading a disk, which significantly reduces the backup time.