Backup LevelsBackup levels come from the architecture of the UNIX dump program. Each backup level is defined by a timestamp in the dumpdates (or amandadates) file, which is structured as:
filesystem level timestampThis tells when the last backup at each level was done. A Level 0 backup always backs up the complete disk, while a Level 1 backup copies all the files and directories changed since the last Level 0. A Level 2 backup copies all the files and directories changed since the last Level 1. Therefore, to perform differential backups, you would use only Levels 0 and 1, while to perform traditional 5-day incrementals with weekly full backups, you would use a cycle of: 0,1,2,3,4,5,0. Amanda follows a mix of strategies that enables it to use incremental backups by bumping the tape level when the tape space to be saved is significant, but also provide redundancy by keeping multiple backups from the same level in the course of a single dumpcycle. |