SQL Server 2017 Administrator's Guide

Differential backup

SQL Server maintains an internal structure called a differential map. This structure maps all changes are done in database extends from the last full backup. This is very useful in cases when a transaction log backup is executed often. Let's see an example where the administrator needs to back up a database on a daily basis, similar to our example in the transaction log backup section, but the transaction log backup is executed every ten minutes. It leads to six transaction log backups every hour and to more than a hundred transaction log backups every day. Such an amount of backup raises a risk of unreadability or loss of certain backups and also increases time spent by the restore process. To reduce the risks and the ...