====== Backup SW ======

===== rsync =====
  * can be used over own proto without encryption (ssh) overhead
  * no build-in incremental snapshots support 
  * incremental backups of modified files possible (using --backup and --backup-dir params)

==== delete files ====
<code bash>
rsync --delete-missing-args --backup --files-from list_file_to_delete.txt src/ 192.168.1.1::root/
</code>


===== rsnapshot =====
  * like rsync
  * incremental snapshots support. Each snapshoot looks like full source tree. Space is not wasted because hardlinks are used.

===== rdiff-backup =====
  * Mirrored structure is available at destination (like rsync). Easy to browse.
  * ACL and extended attributes support
  * Update is slow 
  * special directory ''rdiff-backup-data'' are also created at dest where old versions are kept
  * [[http://www.nongnu.org/rdiff-backup/]]
  * <code>sudo apt-get install python-pylibacl python-xattr</code>

===== duplicity =====
  * No direct access to backups. Backups are stored in PGP encrypted/compressed tar volumes.
  * Restarting of broken backup needs only to re-download first volume from destination


===== duply =====
  * front end to duplicity

<code bash>
duply my-backup backup
duply my-backup cleanup --extra-clean --force
</code>

====== Performance ======
Backups to NSA310 over fast ethernet. Hard disc encrypted with software ARM-optimized AES. Average network copy performance 6-8MB/s.
About 22GB of small files.

^  proto  ^  tool          ^ initial copy ^  update no changes  ^  1GB added ^ 1GB removed ^
|  rsync  | rsync          |              |  22s                |  3m25      |  0m34       |
|  ssh    | rdiff-backup   | 144m (2:24)  |  12m                |  18m       |  19m        |
|  rsync  | rsnapshot      |              |                     |            |             |