Backup

softwares

  • BackInTime gui Sauvegarde de données
  • timeshift gui Sauvegarde du système et fichiers de conf système. permet de restaurer un système.
  • rdiff-backup: incremental, the last backup contains the diff compared to the previous one and so on. if a run failed (network issue) then all following backups are irrelevant.
  • rsnapshot: Based on rsync. Designed to pull backup from a server. So it is good from server to server. pushing to nfs works but is not the intended use of this program. what is the behaviour in case of interrupted backup? use hard links to store only diff. the most recent backup is a mirror of the source dir. older backup dirs are hard links to this miror or files modified.
  • rsync: not impacted in case of network failure, the next run will update the missing files. --backup option can save the diffs compared to previous run, althouth it does not tell is the file is modified or deleted. with a dedicated script, rsync can provide a mirror + some info about what file was modified when.

Rsync

rsync basics

Files permissions and ownership

In order to preserve permissions, rsync must bu run as root. Indeed, as a normal user you can't create files that don't belong to you, so you need to either log in as root on the destination, or you have to be root locally and run rsync in the opposite direction and pull the files in.

By default rsync will try to match the ownership by username / groupname. In other words when the user toto is the owner of a file at the source, rsync will make the user toto also the owner at the destination (even when they have different UID/GID numbers).
That is usually quite resilient and the most predictable for humans as we normally don't look at ownership in the form of UID/GID numbers.

When no matching user toto is present on the remote destination, then a fall-back scenario will happen. Rsync will then preserve the actual underlying UID/GID numbers of the toto user on the source will used to set the owner.

That should preserver the correct ownership when you reverse the rsync direction and restore the backup.

If the option --numeric-ids is used, rsync don't try to match username / groupname of the source / destination and the numeric ID from the source system is used.

source and destination

source and destination can be - local (including usb device), nfs share. - remote using ssh using user@host:backup_dir/

best practices

  • always use sudo to call rsync (to grant ability to check/modify ownership/permissions)
  • mind the / at the end of the path (dir of files inside the dir)
  • use ssh key (paswordless)
  • call with cron via a scrit preventing multiple calls of the same script

options

basic use
---------
rsync -avzh  --progress                        #rsync-copy
rsync -avzh  --progress --remove-source-files  #rsync-move
rsync -avzhu --progress                        #rsync-update
rsync -avzhu --progress --delete               #rsync-synchronize

option utiles
-------------
-a : same as -rlptgoD
             -r       : --recursive
              -l      : keep sym link as they are 
               -ptgoD : preserve owner group perms device time
-s, --protect-args      : don't interpret wildcards in filename 
-z, --compress
-u, --update            : skip files that are newer on the receiver
-n, --dry-run           : trial run with no changes made
-i, --itemize-changes   : output a change-summary for all updates
-H, --hard-links        : preserve hard links
--remove-source-files   : sender removes synchronized files (non-dir)
--delete                : delete extraneous files from dest dirs
-v, --verbose
-h, --human-readable
--exclude=tmp/ 
-backup --backup-dir=rsync_trash/ (use also --exclude=rsync_trash/ )
--files-from=FILE : To specify the exact list of files to transfer

backup

sudo rsync -avh --progress --delete /home/cheperboy/poubelle/source/ /media/debhp/backup_asus/rsync

diff

print a diff considering also file permission and ownership

sudo rsync -ani --delete source/ dest
sudo rsync -aHAX -ni --delete source/ dest      # more complete

restore

sudo rsync -avh --delete /media/debhp/backup_asus/rsync/ /home/cheperboy/poubelle/source

restore snapshot

sudo rsync -avh --delete /media/debhp/backup_asus/root/hourly.0/test/home/cheperboy/poubelle/source/ /home/cheperboy/poubelle/rsnapshot_restore

Rsnapshot

sudo rsnapshot -c /etc/rsnapshot_config_file.conf configtest
sudo rsnapshot du
sudo rsnapshot hourly

sauvegarde distante du dernier snapshot

rsync -avh --delete --progress dest/hourly.0/ distant_backup/
ajouter -x pour compresser le transfert. supprimer --progress si pas en console.

Exemple config rsnapshot overs NFS

from client asus /home/cheperboy/poubelle/source/ to server debhp /media/dd1t/backup_asus/test

server side, setup nfs share: edit /etc/exports

/media/dd1t/backup_asus asus(rw,sync,no_root_squash,no_subtree_check)

client side, mount nfs share: edit /etc/fstab then sudo mount -a

debhp:/media/dd1t/backup_asus /media/debhp/backup_asus nfs defaults 0 0

Client side, edit /etc/rsnapshot_debhp.conf.conf

config_version  1.2
snapshot_root   /media/debhp/backup_asus/root
no_create_root  1
cmd_cp      /bin/cp
cmd_rm      /bin/rm
cmd_rsync   /usr/bin/rsync
cmd_logger  /usr/bin/logger
retain  hourly  6
retain  daily   7
retain  weekly  4
retain  monthly 2
verbose     4
loglevel    3
logfile /var/log/rsnapshot.log
lockfile    /var/run/rsnapshot.pid
link_dest   1
backup  /home/cheperboy/poubelle/source/    test/

Create the snapshot_root directory. When the nfs share is not mounted, this directory won't be created thanks to no_create_root 1. This avoid filling the client disk.

mkdir -r /media/debhp/backup_asus/root

run 

sudo rsnapshot -c rsnapshot_debhp.conf.conf hourly

Check

sudo rsnapshot -c rsnapshot_debhp.conf.conf du