Chapter 4 · System Maintenance and Operations·v1.0.0·Updated 7/7/2026·~13 min
What's changed: Initial version (topic 2.04, subtopics 2.04.1–2.04.6)
4.2Backup and Restore
Key points
Learn backup fundamentals (full, differential, and incremental), representative backup software (Amanda, Bacula, Bareos, BackupPC), media (tape, HDD, optical), and the commands used to perform backups (dd, tar, mt, rsync).
The last line of defense against failure, mistakes, and disaster is the backup. Designing what to back up, how often, on what medium, and how to restore is an operations responsibility—misunderstanding the tradeoffs leads to recovery taking far longer than planned.
4.2.1Backup strategies and media
- Full backup = the entire target saved every time (simplest restore; largest size and time). Differential backup = only changes since the last full (restore needs full + latest differential, two pieces). Incremental backup = only changes since the last backup of any kind (smallest size; restore needs full + every incremental in sequence).
- Backups are taken at the file level, block level, or as a full disk image—the choice depends on the target and how fast restore must be.
- Media: tape (high capacity, cheap, good for long-term archival), HDD (fast, random access), optical media (portable, low capacity). Tape devices are referenced as /dev/st* (rewinding) and /dev/nst* (non-rewinding).
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