SEP sesam provides four different backup levels: full, differential, incremental and copy. The backup level is specified when creating a backup event in the Main Selection -> Scheduling -> Schedules -> New Backup Event.
The following backup levels are available:
A FULL backup always copies all data specified by the backup task, regardless of whether it has been changed or not. A saveset created as FULL is the basic saveset for subsequent DIFF or INCR savesets. While the backup time of a full backup can be significant, restore is fast and simple since only one backup saveset is required. Information about the backup status is stored in the SEP sesam database. Note that the archive bits are not deleted on Windows systems. If you want to force-reset of the archive bits, you can enter the command -o clear_archive in the backup options.
A DIFF (differential) backup saves only data which was created or changed after the last FULL saveset had been created (of the same task). A differential backup is faster than a full backup, however, to restore the whole data source, first the saveset of the full backup has to be restored followed by restore of the DIFF saveset. For this, SEP sesam provides generation restore that enables browsing for and selecting for restore all generations of backed up files since the last full backup.
An INCR (incremental) backup saves only data which was created or changed after the last backup (FULL, DIFF or INCR) of the same task. This is the fastest backup method and requires the least storage space. Restoring from incremental backups is the slowest, because it requires all related savesets to be copied back – the saveset of the last full backup as well as all INC backups. You should consider the advantages of time and resources when planning your backup strategy. A combination of FULL backups stored to tape drives, and DIFF or INC backups stored to virtual disk media is a common method.
A COPY backup is a full backup that has no influence on following differential (DIFF) or incremental (INCR) backups. For the treatment of archive bits, see FULL backup above. COPY backup is usually used for additional full backups, e.g., monthly backups, or backups for archiving, i.e. removal from storage.
|In case no initial FULL backup exists, differential (DIFF) or incremental (INCR) backups are automatically performed as FULL backups.|