The express full backup method is based on monitoring Exchange database files performed by Acronis Express Backup Driver.
Beginning from the first regular full backup, the driver monitors all modifications performed on the database file. The driver determines the offsets and regions of the database file modified by Exchange and stores information about these modifications in the list of changed file regions.
At the next backup, the driver provides the list to the agent and the agent starts to back up only the data corresponding to this list. The agent transfers only the changes and the data that cannot be deduplicated (transaction log files and database page headers). Since the unchanged data is already stored in the deduplicating vault, the agent only adds links to this data. After that, deduplication at target is performed in the same way as for disk-level and file-level backups.
What happens in case of an unexpected system shutdown?
An unexpected system shutdown between the express full backups invalidates information maintained by the Express Backup Driver. At the next backup, Acronis Backup runs the data re-sync backup operation by comparing the current database files with the most recent backup rather than performing a regular full database backup. Although the re-sync increases the number of I/O requests to the production server, it still saves storage space and network traffic. The next backups after the "re-synced" backup will proceed as regular express full backups.
What if one of the scheduled backups fails?
If one or more of the scheduled express full backups fail, the next successful backup will be a regular express full backup based on differences since the previous successful backup.
What happens when maintenance operations involve rebooting of the Exchange server?
If Exchange server reboot is part of maintenance operations, the next successful backup will be a regular express full backup.