Differential backup
Each data extent consists of eight contiguous physically data pages. When changes are made to the pages in an extent, a flag is set to indicate that a change has been made to the extent. When the differential database backup is executed, only those modified extents are written to the backup.
- It backs up all data that has changed since the last full backup.
- Without full backup, differential backup is meaningless, it’s a base of differential backup
- Must be used in conjection with a full backup
- It is available for databases, files and filegroups.
- Under simple recovery model, file and filegroup backup are available for read-only filegroups.
- Differential backups can be used to reduce amount of time required to restore a database.
- It captures only the database extents that have changed since the last full database backup.
- It eliminates the need to apply any transaction log backups that have occurred from the time of the last full backup up until the completion of the differential backup. ( daily basis )
BACKUP DATABASE [AdventureWorks] TO DISK = N’C:\backup\Adventureworks_Diff2.bak’ WITH DIFFERENTIAL , NOFORMAT, INIT, NAME = N’AdventureWorks-Differential Database Backup’, SKIP, NOREWIND, NOUNLOAD, STATS = 10
Tags: Differential Backup, Extent