Database backup
Backs up the databases (EDB), transaction logs (LOG), checkpoint files (CHK), and then truncates the transaction logs for a specific database.
A full backup of an Exchange database creates and stores a complete copy of the database file, transaction logs, and checkpoint files. A Microsoft Exchange Server 2010/2013/2016/2019 database has one set of transaction log files dedicated to that one database.
After the database has been backed up, the transaction log files on the disk are truncated so that only database changes that occur after the backup was made will remain. During this process, either the Store Writer or the Replication Service deletes all log entries up to the checkpoint, based on the assumption that the databases have now been backed up in a consistent state that contains all changes up to the most recent checkpoint.
If the database being backed up is dismounted during the backup operation, Exchange Server 2010 will not truncate the transaction logs and the result will be the equivalent of a copy backup operation, not a Full backup operation.
At the completion of Full or Incremental backups, the headers of the active mounted database get updated with the current backup information. A Full backup is required in order to run Incremental or Differential backups. There is no restriction as to which copy the Full backups are taken from as long as it is a backup.
Full backups are used in the following restoration scenarios: