Brioche Backup

+ +++ + + + + + + + + + + + +

Author:	Amand Tihon
Contact:	<amand.tihon@alrj.org>
Version:	1.0
Date:	Jan 5th, 2008
Copyright:	GNU GPL, see copyright file.

+ +

Abstract

Brioche is yet another backup shell script. Its main features are

Full and differential backups
LVM snapshots
Xen+paravirt oriented (somehow)
Soon: Upload to a distant FTP server.

Rationale

Large numbers of backup solutions are freely available today, but when playing +with incremental or differential backups, most of them rely on some filesystem +capabilities, like hard-linking. If the only remote location available to +store the backups is an FTP server, this is not a solution. +Brioche relies on GNU tar's --listed-incremental option to create real +differential [1] archives.

A second feature that makes Brioche interresting is the ability to use LVM +snapshots. In the case of a Xen setup where the domUs use logical volumes as +partitions, Brioche is able to backup everything from the dom0.

+ + + + + +

[1]	Each differential backup is based upon the last full backup, unlike +incremental, which are based upon the last (full or incremental) backup.

Getting Brioche

You can download the tarball from http://www.alrj.org/projects/brioche +or get the latest development version with the following git command:

+git clone http://git.alrj.org/brioche.git
+

Installation

Copy the three files brioche, brioche.conf and briochetab where +you like, and set the CONFIG_FILE variable in the brioche script +accordingly. If needed, run chmod +x /path/to/brioche.

Using Brioche

Configuration

Edit the file brioche.conf to suit your needs. Each option is commented +inline and will be detailed here.

BACKUPTAB: Full absolute path to the briochetab file. This file describes which logical +volumes and partitions must be backed up. Its format is explained in the +Defining backups section.
MAILTO: When the job is done, Brioche will send a summary of the operations by email. +You can set it to any value that your mail command understands.

REPODIR: Brioche will store all the generated archives in this directory.Note that +before doing a full backup, Brioche will move all previous archives into an +"undo" subdirectory, which will be removed only if the backup is successful. +Make sure there's enough free space on the device where REPODIR is located.
USAGE_WARN: The report email will include a warning if the space used on REPODIR goes +beyond the given threshold. The value must be an integer.
COMPRESS: This directive allows to specify the compression method to apply to the +archives. Possible values are "gz", "bz2" and "lzma". Warning : lzma may +not be available with older versions of GNU tar.
TAR_OPTS: Additionnal options that you may want to pass to tar. A typical value could +be "--one-filesystem -S". The first option will skip all other mointpoints +(very usefull if you have /dev, /proc, /sys or REPODIR mounted under a device +that must be archived). The second one will try to deal with sparse files.
SNAPSHOT_MOUNTPOINT: Sets the directory where the temporary LVM snapshots must be mounted.
SNAPSHOT_NAME: The name to use for the snapshot volumes.
SNAPSHOT_SIZE: Set the size of the snapshot volume. The same suffix than for lvcreate(8) +are available.
USE_FTP: Still TODO.

Defining backups

The backups are defined in the file birochetab. Here is a typical example +for a Xen config where cottman is the dom0 and syrtis, kadarin, valeron are +domUs

+# Partition or LV           Snapshot    Host name     Volume name
+# ---------------------------------------------------------------
+/                           no          cottman       root
+/usr                        no          cottman       usr
+
+/dev/vg00/valeron-root      yes         valeron       root
+
+/dev/vg00/kadarin-root      yes         kadarin       root
+/dev/vg00/kadarin-home      yes         kadarin       home
+
+/dev/vg00/syrtis-root       yes         syrtis        root
+/dev/vg00/syrtis-home       yes         syrtis        home
+/dev/vg00/syrtis-usr        yes         syrtis        usr
+/dev/vg00/syrtis-var        yes         syrtis        var
+

Blank lines, or lines beginning with # are ignored.

The first column defines the directory or logical volume to backup. In this +example,the first two lines are plain directories, while the other ones point +to LVM devices.

The second column specify if the backup should be taken from an LVM snapshot or +not. It must be set to "no" for the backup of a directory and to "yes" for +the backup of a logical volume.

The last two columns are more or less cosmetic, and define where the archive +files will be stored, and how they'll be named. The destination directory will +be created under the REPODIR, and its name will be the value on the third +column. Inside this directory, archive files will be named from the value given +in the fourth column. For instance, a full and a differential backup for +valeron would lead to the following structure

+user:/REPODIR$ ls -l valeron/
+total 356544
+-rw-r--r-- 1 root root 363545613 Jan  3 03:10 root.full.20090103.tar.bz2
+-rw-r--r-- 1 root root    504722 Jan  3 03:10 root.full.snar
+-rw-r--r-- 1 root root    504725 Jan  4 04:06 root.incr.20090104.snar
+-rw-r--r-- 1 root root    160542 Jan  4 04:06 root.incr.20090104.tar.bz2
+

Running Brioche

Brioche understands the following arguments:

+ +++ + + + + + +

+`-f, --full`	Do a full backup (by default, brioche will do a differential).
+`-h, --help`	Show a very limited help.

When everything is ready, execute the brioche script as root. The +script is pretty verbose, so don't panic if you see lots of lines scrolling in +your terminal. By default, Brioche will try to make differential backups, but +will gracefully fall back and do a full backup if none is available.

If all is fine, it can be added in the system crontab. Here's a suggestion for +weekly full backup on Sunday, with differential during the weekdays

+# Daily incremental backup
+30  3  *  *  1-6  /usr/local/bin/brioche > /var/log/backup.`date "+%a"`.log 2>&1
+# Weekly full backup on Sunday
+30  3  *  *  0  /usr/local/bin/brioche -f > /var/log/backup.`date "+%a"`.log 2>&1
+

The output of the script will be saved in /var/log/backup.DOW.log with DOW +being the abbreviated day of the week (see man date(1) for the format).

Bug reporting

There's no bugtracker for this project, your bug reports should be sent to the +author : Amand Tihon <amand.tihon@alrj.org>. Please include as much information +as possible in your report.

References

GNU tar documentation : http://www.gnu.org/software/tar/manual/
LVM documentation and links : http://sourceware.org/lvm2/