From v19.2, changed block tracking (CBT) can be enabled on the Data Management Agent. CBT offers a way of speeding up backups by scanning only those data blocks in the backup selection that have changed since the previous backup for changes, instead of whole files.
- Volume shadow copying (VSS) makes it possible to identify the differences in data blocks between backups and must therefore be enabled for CBT to work.
- CBT is not compatible with local copy. For local copy, we read and process entire files instead of patch chains. Since the purpose of CBT is to negate the need to process entire files, the feature is not compatible with local copy. Enabling local copy will automatically disable CBT, and this will be noted in the logs.
- It is recommended that CBT be used only on systems where large files are routinely modified. CBT is not ideal for servers where files are added or removed but not modified.
How to enable CBT
Open the ESE Agent and go to Options and Settings > Advanced. Under VSS, tick Use changed block tracking (CBT) for faster backups.
You can also specify what should happen in cases where CBT fails (abort the backup completely or continue with a standard backup without CBT).