archive-rotator 0.1.0

Flexible utility for rotating backup files.

Flexible utility for rotating backup files.

• Free software: MIT license

• Documentation: https://archive-rotator.readthedocs.org.

This utilty rotates files - typically backup archives. It offers three rotation algorithms - FIFO, Tower of Hanoi, and tiered (a generalization of grandfather-father-son). It requires no configuration file, just command-line parameters. The script is stand-alone (python required) and tracks its state by applying a naming convention to rotated files.

See http://en.wikipedia.org/wiki/Backup_rotation_scheme

https://github.com/maxharp3r/archive-rotator

Use Case

We assume that you have an archive, say /path/to/foo/mydump.tgz that is the result of an external process (e.g., tar -czf, or mysqldump) that recurs (e.g., using cron). You will use this script to add this file into a rotation set. If the size of the set is greater than the maximum number of files to keep (configurable), then the rotation set will be trimmed according to a rotation algorithm, which is configurable.

Example of running:

archive-rotator -v -n 5 /path/to/foo/mydump.tgz

This will rename mydump.tgz to something like this:

/path/to/foo/mydump.tgz.2012-12-20-133640.backup-0

Given this configuration, the rotation script automatically keep at most 5 files in the rotation. When the script is run six times, the set of archives would be too big, so the oldest will be deleted. This is an example of the simple (FIFO) rotation algorithm.

Running

Run archive-rotator -h for documentation of command-line parameters.

Algorithms

FIFO (simple)

This rotation scheme keeps the last n archives. It emphasizes recency at the cost of history and/or disk space.

Tower of Hanoi

This rotation scheme is described here: http://en.wikipedia.org/wiki/Backup_rotation_scheme#Tower_of_Hanoi It emphasizes long history and saving disk space, but is not very tunable.

Example of running:

archive-rotator –hanoi -v -n 6 /path/to/foo/mydump.tgz

Given this configuration, the rotation script automatically keep at most 6 files in the rotation, rotated every 1, 2, 4, 8, 16, and 32 runs, respectively. So, after 32 rotations, the directory will look something like this:

/path/to/foo/mydump.tgz.2013-01-03-094732.backup-16 /path/to/foo/mydump.tgz.2013-01-03-094734.backup-24 /path/to/foo/mydump.tgz.2013-01-03-094735.backup-28 /path/to/foo/mydump.tgz.2013-01-03-094736.backup-30 /path/to/foo/mydump.tgz.2013-01-03-094737.backup-31 /path/to/foo/mydump.tgz.2013-01-03-094738.backup-32

Tiered

This is a generalization of the grandfather-father-son rotation algorithm (described here - http://en.wikipedia.org/wiki/Backup_rotation_scheme#Grandfather-father-son). This algorithm is capable of handling a variety of rotation schedules.

This algorithm, unlike the others, accepts a list of one or more -n configurations. Each one is a “tier”. For example:

# three tiers: the first will hold 6 files, the second will hold 3, the third will hold 12 archive-rotator –tiered -v -n 6 -n 3 -n 12 /path/to/foo/mydump.tgz

If the example above were run daily, we’d approximate 6 daily, 3 weekly, and 12 monthly backups in the rotation set.

You may configure any number of slots to each tier. If we have a single tier with 8 slots, the algorithm will behave identically to the FIFO algorithm configured with eight slots. If we add a second tier with two slots, then the algorithm will fill one of those two second-tier slots every ninth run. If we add a third tier with one slot, then the algorithm will put the archive into the third tier slot for every two it puts into the second tier.

Two tier example: -n 3 -n 2. id : 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 … maps to slot: 0 1 2 3 0 1 2 7 0 1 2 3 0 1 2 … tier: : 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 …

Three tier example: -n 2 -n 2 -n 2. id : 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 … maps to slot: 0 1 2 0 1 5 0 1 8 0 1 2 0 1 5 … tier: : 0 0 1 0 0 1 0 0 2 0 0 1 0 0 1 …

If we have tiers of size j, k, l, and m, then m is rotated every (j+1)(k+1)(l+1) runs.

This algorithm can replicate the behavior of both FIFO and Tower of Hanoi.

# FIFO with 6 slots: archive-rotator –tiered -v -n 6 /path/to/foo/mydump.tgz # hanoi with 4 slots: archive-rotator –tiered -v -n 1 -n 1 -n 1 -n 1 /path/to/foo/mydump.tgz

Credits

Tools used in rendering this package:

• Cookiecutter

• cookiecutter-pypackage

History

0.1.0 (2015-11-23)

• First release on PyPI.