Use the dump transaction command to make routine backups of your transaction log.
dump transaction is similar to the incremental backups provided by many operating systems. It copies the transaction log, providing a record of any database changes made since the last transaction log dump. After dump transaction has copied the log, it truncates the inactive portion.
dump transaction takes less time and storage space than a full database backup, and it is usually run more often. Users can continue to make changes to the database while the dump is taking place. You can run dump transaction only if the database stores its log on a separate segment.
After a media failure, use the with no_truncate option of dump transaction to back up your transaction log. This provides a record of the transaction log up to the time of the failure.