Difference between revisions of "System backup"

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(Using a script: as of december 9 2013 the script doesn't exlude all paths correctly- corrected the rsync command in the script)
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[[Category:System recovery]]
 
[[Category:System recovery]]
[[cs:Full System Backup with rsync]]
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[[cs:Full system backup with rsync]]
{{Article summary start}}
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[[es:Full system backup with rsync]]
{{Article summary text|Instructions on backing up the root tree, creating a bootable copy of your system, or for transferring your system to a new drive or partition.}}
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[[ja:Rsync によるフルシステムバックアップ]]
{{Article summary heading|Related}}
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[[zh-hant:Full system backup with rsync]]
{{Article summary wiki|Backup Programs}}
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{{Related articles start}}
{{Article summary wiki|rsync}}
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{{Related|Synchronization and backup programs}}
{{Article summary end}}
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{{Related|System maintenance#Backup}}
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{{Related|Disk cloning}}
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{{Related|Migrate installation to new hardware}}
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{{Related|File recovery}}
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{{Related articles end}}
  
This article is about using [[rsync]] to transfer a copy of your "/" tree, excluding a few select folders. This approach is considered to be better than [[disk cloning]] with {{ic|dd}} since it allows for a different size, partition table and filesystem to be used, and better than copying with {{ic|cp -a}} as well, because it allows greater control over file permissions, attributes, Access Control Lists (ACLs) and extended attributes. [http://www.bestbits.at/acl/about.html]
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It is important to regularly backup system and user data stored for example in {{ic|/etc}}, {{ic|/home}}, {{ic|/var}} and for server installations, also {{ic|/srv}}.
  
Either method will work even while the system is running. Since it's going to take a while, you may freely browse the web during this time. Worst case scenario you won't get the same opened tabs when you restore the backup (or boot from it) because they weren't saved. Not a big deal.
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== Using Btrfs snapshots ==
  
== With a single command ==
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See [[Btrfs#Snapshots]] and [[Snapper]].
  
As root, run:
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== Using LVM snapshots ==
  
# rsync -aAXv /* /path/to/backup/folder --exclude={/dev/*,/proc/*,/sys/*,/tmp/*,/run/*,/mnt/*,/media/*,/lost+found}
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See [[LVM#Snapshots]] and [[Create root filesystem snapshots with LVM]].
For information on why these folders were excluded, read the next section.
 
  
{{Note|If you are heavy user of '''hardlinks''', you might consider using additionally '''{{ic|-H}}''' {{ic|rsync}}'s option, which by default is turned off as memory expensive during rsync run, but nowadays it should be no problem on most of modern machines. There are a lot of hard links below the /usr folder which save disk space.}}
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== Using rsync ==
  
{{Note|If you plan on backing up your system somewhere other than {{ic|/mnt}} or {{ic|/media}}, don't forget to add it to the list, to avoid an infinite loop.  Also, if there are any bind mounts in the system they should be excluded as well, as not to copy the bind mounted contents twice.  The example below is a good place to start and excludes all the necessary directories that are typically common to all users of Arch Linux.  Your system may have additional areas which you may also want to exclude.  Use the {{ic|mount}} command to list system mounts for additional insight on what to exclude.}}
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See [[rsync#As a backup utility]].
  
{{Note|You may want to add rsync's '''{{ic|--delete}}''' option if you are running this multiple times to the same backup folder}}
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== Using tar ==
  
== Using a script ==
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See [[Full system backup with tar]].
  
Same as in the above method, the system files are transferred in archive mode, ensuring that symbolic links, devices, permissions and ownerships, among other file attributes are preserved, while excluding files that match the patterns from the {{ic|--exclude}} string. On top of that, it shows at the end how much time it took, and it also writes a blank file stating when the backup was created. To learn more about what this script does, read {{ic|man rsync}} and {{ic|man date}}.
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== Bootable backup ==
  
{{Note|Again, if you plan on backing up your system somewhere other than {{ic|/mnt}} or {{ic|/media}}, don't forget to add it to the list, to avoid an infinite loop.}}
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Having a bootable backup can be useful in case the filesystem becomes corrupt or if an update breaks the system. The backup can also be used as a test bed for updates, with the ''testing'' repo enabled, etc. If you transferred the system to a different partition or drive and you want to boot it, the process is as simple as updating the backup's {{ic|/etc/fstab}} and your bootloader's configuration file.
  
{{Note|You may want to add rsync's '''{{ic|--delete}}''' option if you are running this multiple times to the same backup folder}}
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This section assumes that you backed up the system to another drive or partition, that your current bootloader is working fine, and that you want to boot from the backup as well.
 
 
{{hc|$ cd ~/Scripts
 
$ nano backup.sh|<nowiki>
 
#!/bin/sh
 
 
 
if [ $# -lt 1 ]; then
 
    echo "No destination defined. Usage: $0 destination" >&2
 
    exit 1
 
elif [ $# -gt 1 ]; then
 
    echo "Too many arguments. Usage: $0 destination" >&2
 
    exit 1
 
elif [ ! -d "$1" ]; then
 
  echo "Invalid path: $1" >&2
 
  exit 1
 
elif [ ! -w "$1" ]; then
 
  echo "Directory not writable: $1" >&2
 
  exit 1
 
fi
 
 
 
case "$1" in
 
  "/mnt") ;;
 
  "/mnt/"*) ;;
 
  "/media") ;;
 
  "/media/"*) ;;
 
  *) echo "Destination not allowed." >&2
 
    exit 1
 
    ;;
 
esac
 
 
 
START=$(date +%s)
 
rsync -aAXv /* $1 --exclude={/dev/*,/proc/*,/sys/*,/tmp/*,/run/*,/mnt/*,/media/*,/lost+found,/var/lib/pacman/sync/*}
 
FINISH=$(date +%s)
 
echo "total time: $(( ($FINISH-$START) / 60 )) minutes, $(( ($FINISH-$START) % 60 )) seconds"
 
 
 
touch $1/"Backup from $(date '+%A, %d %B %Y, %T')"</nowiki>}}
 
 
 
$ chmod +x backup.sh
 
 
 
{{Note|The contents of {{ic|/dev}}, {{ic|/proc}}, {{ic|/sys}}, {{ic|/tmp}}, {{ic|/run}} were excluded because they are populated at boot (while the folders themselves are ''not'' created), {{ic|/lost+found}} is filesystem-specific. For Arch Linux, {{ic|/var/lib/pacman/sync/*}} can also be excluded. This can save a lot of time on every backup since the directory contains many small files that tend to change quite often. These are description files for every package from the repositories and can be re-generated with {{ic|pacman -Syu}}. Additionally, you may also want to skip {{ic|/home/*/.thumbnails/*}}, {{ic|/home/*/.mozilla/firefox/*.default/Cache/*}} and {{ic|/home/*/.cache/chromium/*}}.}}
 
 
 
Backing up is easy.
 
 
 
While the system is running, open up a terminal and run (as root):
 
 
 
# /home/user/Scripts/backup.sh /some/destination
 
(replace user with username since you created the directory as user in the user's home directory)
 
 
 
You can also replace both {{ic|$1}} instances from the script with the actual destination path, move it to one of the folders from {{ic|echo $PATH}}, and then simply run (as root):
 
 
 
# backup.sh
 
 
 
== Boot requirements ==
 
 
 
Having a bootable backup can be useful in case the filesystem becomes corrupt or if an update breaks the system. The backup can also be used as a test bed for updates, with the [testing] repo enabled, etc. If you transferred the system to a different partition or drive and you want to boot it, the process is as simple as updating the backup's {{ic|/etc/fstab}} and your bootloader's configuration file.
 
  
 
=== Update the fstab ===
 
=== Update the fstab ===
  
Without rebooting, edit the backup's [[fstab]] to reflect the changes:
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Without rebooting, edit the backup's [[fstab]] by commenting out or removing any existing entries. Add one entry for the partition containing the backup like the example here:
{{hc|# nano /path/to/backup/etc/fstab|2=
 
tmpfs        /tmp          tmpfs    nodev,nosuid            0  0
 
  
<font color=#888888><i>/dev/sda1    /boot        ext2      defaults                0  2
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/dev/sda''X''   /            ''ext4''     defaults                0  1
/dev/sda5    none          swap      defaults                0  0
 
/dev/sda6   /            ext4      defaults                0  1
 
/dev/sda7    /home        ext4      defaults                0  2</i></font>}}
 
  
Because rsync has performed a recursive copy of the ''entire'' root filesystem, all of the {{ic|sda}} mountpoints are problematic and booting the backup will fail. In this example, all of the offending entries are replaced with a single one:
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Remember to use the proper device name and filesystem type.
  
{{hc|# nano /path/to/backup/etc/fstab|
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=== Update the bootloader's configuration file ===
tmpfs        /tmp          tmpfs    nodev,nosuid            0  0
 
  
/dev/'''sdb1'''    /            ext4      defaults                0  1}}
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For [[Syslinux]], all you need to do is duplicate the current entry, except pointing to a different drive or partition.
  
Remember to use the proper device name and filesystem type.
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{{Tip|Instead of editing {{ic|syslinux.cfg}}, you can also temporarily edit the menu during boot. When the menu shows up, press the {{ic|Tab}} key and change the relevant entries. Partitions are counted from one, drives are counted from zero.}}
  
=== Update the bootloader's configuration file ===
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For [[GRUB]], it is recommended that you automatically [[GRUB#Generate_the_main_configuration_file|re-generate the main configuration file]].  If you want to freshly install all grub files to somewhere other than {{ic|/boot}}, such as {{ic|/mnt/newroot/boot}}, use the {{ic|--boot-directory}} flag.
  
This section assumes that you backed up the system to another drive or partition, that your current bootloader is working fine, and that you want to boot from the backup as well.
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Also verify the new menu entry in {{ic|/boot/grub/grub.cfg}}. Make sure the UUID is matching the new partition, otherwise it could still boot the old system. Find the UUID of a partition as follows:
  
For [[Syslinux]], all you need to do is duplicate the current entry, except pointing to a different drive or partition:
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# lsblk -no NAME,UUID /dev/sdb3
 
 
{{Tip|Instead of editing {{ic|syslinux.cfg}}, you can also temporarily edit the menu during boot. When the menu shows up, press the {{ic|Tab}} key and change the relevant entries. Partitions are counted from one, drives are counted from zero.}}
 
  
# nano /boot/syslinux/syslinux.cfg
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where you substitute the desired partition for /dev/sdb3. To list the UUIDs of partitions grub thinks it can boot, use grep:
  
For [[GRUB]], it's recommended that you automatically re-generate the {{ic|grub.cfg}} file:
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# grep UUID= /boot/grub/grub.cfg
  
# pacman -S os-prober
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=== First boot ===
# grub-mkconfig -o /boot/grub/grub.cfg
 
  
== See also ==
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Reboot the computer and select the right entry in the bootloader. This will load the system for the first time. All peripherals should be detected and the empty folders in {{ic|/}} will be populated.
  
# [http://blog.pointsoftware.ch/index.php/howto-local-and-remote-snapshot-backup-using-rsync-with-hard-links/ Howto – local and remote snapshot backup using rsync with hard links] Includes file deduplication with hard-links, MD5 integrity signature, 'chattr' protection, filter rules, disk quota, retention policy with exponential distribution (backups rotation while saving more recent backups than older)
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Now you can re-edit {{ic|/etc/fstab}} to add the previously removed partitions and mount points.

Latest revision as of 11:15, 1 July 2017

It is important to regularly backup system and user data stored for example in /etc, /home, /var and for server installations, also /srv.

Using Btrfs snapshots

See Btrfs#Snapshots and Snapper.

Using LVM snapshots

See LVM#Snapshots and Create root filesystem snapshots with LVM.

Using rsync

See rsync#As a backup utility.

Using tar

See Full system backup with tar.

Bootable backup

Having a bootable backup can be useful in case the filesystem becomes corrupt or if an update breaks the system. The backup can also be used as a test bed for updates, with the testing repo enabled, etc. If you transferred the system to a different partition or drive and you want to boot it, the process is as simple as updating the backup's /etc/fstab and your bootloader's configuration file.

This section assumes that you backed up the system to another drive or partition, that your current bootloader is working fine, and that you want to boot from the backup as well.

Update the fstab

Without rebooting, edit the backup's fstab by commenting out or removing any existing entries. Add one entry for the partition containing the backup like the example here:

/dev/sdaX    /             ext4      defaults                 0   1

Remember to use the proper device name and filesystem type.

Update the bootloader's configuration file

For Syslinux, all you need to do is duplicate the current entry, except pointing to a different drive or partition.

Tip: Instead of editing syslinux.cfg, you can also temporarily edit the menu during boot. When the menu shows up, press the Tab key and change the relevant entries. Partitions are counted from one, drives are counted from zero.

For GRUB, it is recommended that you automatically re-generate the main configuration file. If you want to freshly install all grub files to somewhere other than /boot, such as /mnt/newroot/boot, use the --boot-directory flag.

Also verify the new menu entry in /boot/grub/grub.cfg. Make sure the UUID is matching the new partition, otherwise it could still boot the old system. Find the UUID of a partition as follows:

# lsblk -no NAME,UUID /dev/sdb3

where you substitute the desired partition for /dev/sdb3. To list the UUIDs of partitions grub thinks it can boot, use grep:

# grep UUID= /boot/grub/grub.cfg

First boot

Reboot the computer and select the right entry in the bootloader. This will load the system for the first time. All peripherals should be detected and the empty folders in / will be populated.

Now you can re-edit /etc/fstab to add the previously removed partitions and mount points.