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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 96 |
1 files changed, 8 insertions, 88 deletions
@@ -68,65 +68,13 @@ client to start and watch the backup. Configuring byteback-backup --------------------------- -You can now set "byteback-backup" on a daily cron job to start backing up the -server on a regular basis. -Without any further options this will copy every file from the root downwards. - -It currently excludes /tmp, /var/tmp, /var/cache/apt/archives, /swap.file and -/var/backups/localhost which (on Bytemark systems) do not need to be part of -any backup. To specify which locations are excluded, add them to -/etc/byteback/excludes, one per line. The filesystems /dev, /proc, /run and -/sys are always excluded. - -It is possible to configure a full rsync filter by creating the file -/etc/byteback/rsync_filter, which is parsed to rsync via the --filter flag. -Note that excludes on the command line take precedence, unless the filter -starts with an exclamation mark, which resets everything. If you do this, -you'll need to specify /proc, /sys, etc manually. See the rsync manpage for -more information about filters. - -It is also possible to add extra rsync flags to the configuration. The -following flags are always set: - - --archive --numeric-ids --delete-during --inplace --relative --timeout 43200 - -If you wish to add to that (e.g. --xattrs --acl --hard-links) then simply add -them to /etc/byteback/rsync_flags. These extra flags get appended after the -default flags above, so they take precedence. - -When the backup has completed successfully, the server will take a snapshot -so that the client can't alter the backups, and then "prune" the backup -snapshots to ensure that the next backup is likely to run OK. - -If the backup is interrupted or dies unexpected, running "byteback backup" -will cause the backup to be resumed, with rsync saving the work of re-copying -any files that hadn't changed. By default this will happen automatically up to -5 times, with a 10 minute pause in between each attempt. +This is now documented in the manapge for byteback-backup(1). Viewing and restoring backups ----------------------------- -Backups can be viewed on the server filesystem, although the permissions will -be wrong. The rsync "fake-super" flag is used to store the permissions in a -user attribute list. To view this list on the server, run - - getfattr -d $filename - -This command is part of the "attr" package in Debian. - -To restore a file you may use the `byteback-restore` command, which allows you to find all files matching a pattern via a command-like: - - byteback-restore --file /etc/passwd - -To actually restore the file, to the current directory, run: - - byteback-restore --file /etc/passwd --revision=current - -Recursive restorations are supported too: - - byteback-restore --file /srv --revision=current - +This is now documented in the manapge for byteback-restore(1). The trust model --------------- @@ -151,43 +99,15 @@ over a long enough period of time: Pruning behaviour ----------------- -Unless you are backing up a very small amount of data, backups will always -need pruning, i.e. old backups must be deleted to make way for newer ones. - -There is a program on the server called byteback-prune which deals with this -operation. It deletes old backups until a certain amount of free space is -achieved, which is currently fixed at 10% free. This can be changed by setting -the --maxpercent option. - -It can choose which backups to delete by one of two methods: -1) the 'age' method simply deletes the oldest backup; - -2) the 'importance' method tries to retain a more spread-out backup pattern -by "scoring" each backup according to how close it is to a set of "target -times". These are: - - * midday today; - * midday on the previous 6 days; - * midday on the previous 4 Sundays; - * midday on every 4th Sunday before that. - -So when you ask the pruner to run, the backup closest to the present time will -be the last one to be deleted. The backup closes to "1 day ago" will be the -second-last, and so on. We score every backup in this way until we end up with -a "least important" snapshot to delete. - -The upshot of the second strategy should be that we retain closely-spaced -daily backups, but as they get too numerous, we make sure that we are reluctant -to delete our very oldest. - -The "4th Sunday" is calculated as every 4th Sunday in the Unix epoch, i.e. -every fourth Sunday since Sunday 4th Jan 1970. +This is now documented in byteback-prune(1). Acknowledgements ---------------- -For maximum portability, I've included two libraries. Thanks very much to +For maximum portability, I've included three libraries. Thanks very much to their authors: -sys-filesystem by Daniel J. Berger: https://github.com/djberg96/sys-filesystem -trollop by William Morgan: https://github.com/wjessop/trollop +* sys-filesystem by Daniel J. Berger: https://github.com/djberg96/sys-filesystem +* trollop by William Morgan: https://github.com/wjessop/trollop +* ffi-xattr by Jari Bakken: https://github.com/jarib/ffi-xattr + |