About backing up all or only uncommitted Exchange transaction log files with snapshot backups
The Back up option for log files during full backups determines how many log files are backed up during a full or user-directed snapshot backup. You can adjust this setting in the host properties for the Exchange client.
If you select NetBackup only backs up and catalogs the transaction log files that were not committed to the Exchange database at the time that the snapshot was taken. Exchange requires these uncommitted log files during the recovery of the Exchange database to make the database consistent. If is selected, all of the log files that exist on the snapshot volume are backed up and cataloged.
is not recommended for replicated environments.
When you back up only the uncommitted log files, the advantage is that less space is needed on the storage unit for the transaction logs. When you back up all of the log files, the advantage is that a consecutive set of log files is maintained. A previous full backup can use these log files for rolling forward. These options do not affect the ability to recover the current full or user-directed type backup. These options do affect the ability to roll forward from a previous full or user-directed type backup.
For example, consider if a full backup is performed, followed by two differential backups, followed by another full backup. If is specified, all of the log files exist in backup images. The first full backup, the log files from the two differential backups, and the log files from the second full backup can be restored. The existence of all the log files allows for a roll-forward recovery. If you select , a gap exists in the sequence of transaction logs that are in the backup images. From the full backup, you can restore only as far as the time that is covered in the two differential backups.
For more information on how to configure the client host properties, see the following topic: