Changed Block Tracking

To perform incremental backup, Veeam Agent for Microsoft Windows needs to know what data blocks have changed since the previous job session. For the volume-level backup, Veeam Agent for Microsoft Windows uses the changed block tracking mechanism, or CBT. CBT increases the speed and efficiency of incremental backups.

To keep track of changed data blocks, Veeam Agent for Microsoft Windows can use the following mechanisms:

• Default CBT mechanism — this mechanism are enabled by default in all installations of Veeam Agent for Microsoft Windows. To learn more, see Default Changed Block Tracking Mechanism.
• Veeam CBT driver — this functionality is available if the Veeam Agent computer runs a Microsoft Windows Server OS and the Server edition of Veeam Agent for Microsoft Windows. To learn more, see Veeam Changed Block Tracking Driver.

For the file-level backup, Veeam Agent does not use CBT. Veeam Agent compares file metadata to retrieve changes. To learn more, see Change tracking for File-Level Backup.