Rdiff-backup

From MineOS
Jump to: navigation, search

Contents

General information

Rdiff-backup is an implementation of the rsync algorithm which combines the benefits of both mirroring and increments. It does this by keeping a mirror of the most current backup intact in the backup directory and then creating patches for each changed file so that each increment can be reached at any time.

Backup accumulation

Over time, with enough file changes and enough backups, the increments will take up a lot of space. This can be cleared with the argument --remove-older-than.

Pruning intervals

There is incredible precision to what degree you want to remove old increments. It is passed as a single, non-spaced argument with all the different units of time:

argument unit of time
30s 30 seconds
45m 45 minutes
12h 12 hours
4D 4 days
1W 1 week
2M 2 months
1Y 1 year
44B 44 backups

These can be combined to make more specific timeframes, such as:

3D12h30m -- 3 days, 12 hours, 30 minutes

Difference between backups and archives

Few people make the distinction between Archives and Backups like MineOS does. There is a fundamental difference between these two, despite them often being used interchangeably.

Archive

The easiest way to understand the distinction between an archive and a backup is the format of an archive. File formats such as .tar are archive formats that simply combine multiple files into one consolidated file. Doing so has many benefits such as fewer file counts, less inode usage, less fragmentation and cluster waste. On the other hand, archived files are not usable in archive form (just like you have to extract a .zip file before you can access its contents).

Backup

Using the rdiff-backup algorithm creates a full miirrored backup of a directory. As a result, this results in at least a +100% use of space. However, because not all files change between backups, files that do not change do not have to be backed up again, which ultimately saves space over repeated backups. Incremental backups using rdiff-backup on files that have relatively low changes (in file count) will save a lot of space in the long run versus accumulating archives.

A full example can be seen in the gray-background area of MineOS Advanced Features Page.