Full Backups
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 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 occurred 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. In replicated deployments, this information will be committed to a transaction log file and replicated to the other DAG copies of the database. Headers of the database copies will get updated as this transaction log file is replayed into the database copy.
A Full shadow copy backup is required in order to run Incremental or Differential shadow copy backups. There is no restriction as to which copy the Full backups are taken from as long as it is a shadow copy backup.
Full backups are used in three different restore scenarios:
A database becomes corrupted or is lost, but the transaction log files on disk are intact. In this scenario, the affected database files can be restored from the Full backup, and then recovered by replaying the transaction logs that are still on disk.
Transaction log files, as well as the database file on disk, are lost. In this scenario, the transaction log files that were backed up at the time of the Full backup are restored together with the database.
Exchange 2010 enables restoring logs without having to restore the applicable database from a Full backup set. This option makes it possible for a previous Full backup to be restored and combined with the transaction log files from the most recent Full backup to roll forward as in the previous two scenarios.
When the VSS_BACKUP_TYPE enumeration in the Volume Shadow Copy Service is set to VSS_BT_FULL while performing a backup with the Store Writer, the following components will be included in the backup:
A database with the logical path Microsoft Exchange Server\Microsoft Information Store\<Server Name>\<Database GUID>
A log file with the logical path Microsoft Exchange Server\Microsoft Information Store\<Server Name>\<Database GUID>
Similarly, if the Full backup is taken from a CAG copy locations using the Replication Writer, the above components will be included in the Full backup with the exception that in the logical file path the \<Server Name> will be pre-pended by \Replica to designate the actual files coming from replica location and the file paths will reflect the DAG copy file location.