Backup data using rdiff-backup

Here summarizes the usages of rdiff-backup to backup files with old version kept also.

Mirror backup and incremental backup

rsync is a great tool and also a great algorithm to mirror your data to different disks for backup usage. However, with a mirror, any changes made to the source directory are immediately sent to the backup directory, and old changes are lost. Therefor backup tools which can save both original files and changes are required. There are at least three tools can do this, rdiff-backup, duplicity, and rsnapshot.

rdiff-backup creates an exact mirror of the latest copy of the data, and stores old versions of files - in fact, diffs between new and old - in a special subdirectory. To recover a file from 4 revisions ago, you start with the latest version and apply the 4 diffs in reverse order. One major disadvantage of rdiff-backup besides from the lack of encryption is that it demands that the server also has installed the exact same version of rdiff-backup.

duplicity, on the other hand, starts with a full copy of the oldest version of the data, and stores new versions of files as diffs between old and new. So to recreate the latest version of a file, you start with the original, and apply all the diffs required to bring it up to date.

Rsnapshot creates a “virtual look” where it appears that each backup is a full backup. Rsnapshot uses hard links to achieve the “virtual look” of full backups. The disk space required is just a little more than the space of one full backup, plus incrementals. This is an important feature if disk space is an issue.

Detailed comparison of these tools are referred in following links.

• rdiff-backup
• duplicity
• rsnapshot
• http://www.saltycrane.com/blog/2008/02/backup-on-linux-rsnapshot-vs-rdiff/
• http://james.lab6.com/2008/07/09/rdiff-backup-and-duplicity/
• http://bitflop.com/document/75
• http://askubuntu.com/questions/2596/comparison-of-backup-tools
• http://www.reddit.com/r/linux/comments/fgmbb/rdiffbackup_duplicity_or_rsnapshot_which_is/

Install rdiff-backup at both local and remote computers

• Install requirements

  #install for ubuntu, debian
  sudo apt-get install python-dev librsync-dev
  #self compile
  #downlaod rsync-dev from https://sourceforge.net/project/showfiles.php?group_id=56125
  tar xvzf librsync-0.9.7.tar.gz
  export CFLAGS="$CFLAGS -fPIC"
  ./configure --prefix=/home/user/rsync --with-pic
  make
  make install
  

• Install rdiff-backup

  python setup.py install --prefix=/home/user/rdiff-backup
  #If you complied rsync-dev yourself, please specify the location of rsync-dev
  python setup.py --librsync-dir=/home/user/rsync install --prefix=/home/user/rdiff-backup
  

• Add exeutable files and python modules to environmental variables

  #Add the following words into .bashrc or .bash_profile or any other config files
  export PATH=${PATH}:/home/user/rdiff-backup/bin
  export PYTHONPATH=${PYTHONPATH}:/home/user/rdiff-backup/lib/python2.x/site-packages
  #pay attention to the x in python2.x of above line
  

• Test environmental variable when executing commands through ssh

  ssh user@host 'echo ${PATH}' #When I run this command in my local computer, 
						       #I found only system environmetal variable is used 
							   #and none of my self-defined environmetal variable is used.
  #Then, I modified the following lines in file 'SetConnections.py' in 
  #/home/user/rdiff-backup/lib/python2.x/site-packages/rdiff_backup
  #to set environmental explicitly when login.
  #pay attention to the single quote used inside double quote
  __cmd_schema = "ssh -C %s 'source ~/.bash_profile; rdiff-backup --server'"
  __cmd_schema_no_compress = "ssh %s 'source ~/.bash_profile; rdiff-backup --server'"
  #choose the one contains environmental variable for rdiff-backup from .bash_profile and .bashrc.
  

Use rdiff-backup

• Run for the first time with --force

  • rdiff-backup --no-compression --force --print-statistics user@host::/home/user/source_dir destination_dir

• Run normal backup without --force

  • rdiff-backup --no-compression --print-statistics user@host::/home/user/source_dir destination_dir

• Timely backup your data

  • Add the above command into crontab (hit 'crontab -e' in terminal to open crontab) in the format like 5 22 */1 * * command which means executing the command at 22:05 everyday.

• Restore data

  • Restore the latest data by running rdiff-backup -r now destination_dir user@host::/home/user/source_dir
  • Restore files 10 days ago by running rdiff-backup -r 10D destination_dir user@host::/home/user/source_dir. Other acceptable time formats include 5m4s (5 minutes 4 seconds) and 2014-01-01 (January 1st, 2014).
  • Restore files from an increment file. Increment files are stored in destination_dir/rdiff-backup-data/increments.