Database backup policies
Choosing a database backup policy method depends primarily on the size of the database and the frequency of the backups. For example, a user who needs to back up a 1 TB database might not be able to perform a backup every hour using the Full dump always policy. However, the backup might be able to accommodate an incremental or differential dump every hour.
• Full dump: Always – Performs a full dump (VSS snapshot) of the database. There are no restrictions on the number of backups. However, a dump time is required for each backup.
• Full dump: Plus differential – Performs a full dump (VSS snapshot) of the database on first backup followed by differential backups until another full backup is required. Differential backups contain all changes to the database since the last full dump, which means less data is transmitted from the source to the DS-Client over the LAN. This could result in possible storage savings on the DS-System because of the size of the differential generations. Even when a Full dump is required, the DS-Client still processes “incremental forever” and sends only the delta changes to the DS-System. Only one backup can back up the target database to maintain a record of differential backups.
• Full dump: Plus incremental – Performs a full dump (VSS snapshot) of the database on first backup followed by incremental backups until another full backup is required. Incremental backups contain all changes to the database since the last full dump, which means less data is transmitted from the source to the DS-Client over the LAN. This could result in possible storage savings on the DS-System because of the size of the incremental generations. Even when a Full dump is required, the DS-Client still processes “incremental forever” and sends only the delta changes to the DS-System. Only one backup can back up the target database to maintain a record of incremental backups. For Microsoft SQL Server backups, the database must be configured with the full or bulk_logged recovery model, which means that more processing will occur and more data and logs will be stored.
• Transaction Log Only (Microsoft SQL Server) – Only transaction logs are backed up. This offers more granular control by allowing you to restore the target database to a specific point in time. Shorter backup times are required because the backup of transaction logs require less data transfer. Requires two steps in the restore process: (1) restore a full database using a Microsoft SQL Server (Classic or VSS-aware) backup, and (2) restore transaction logs from a Microsoft SQL Server (Classic) backup.
• Backup using VSS (Separate VSS-aware backup) – Data is backed up using the Microsoft VSS (Volume Shadow Copy Service), which avoids the dump time for the data. This means more data is transmitted between the source and the DS-Client.