Difference between revisions of "System backup"
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Revision as of 20:50, 30 May 2012
This rsync script allows creating a full backup copy across filesystems. It is setup so that the copy includes intact booting capabilities, optionally excluding selected files.
The approach has benefits over omitting system files by just copying personal data; if the system becomes corrupted in the main partition, overcoming the problem means booting into the backup as opposed to identifying and reinstalling affected programs.
Instructions were converted from this forum post.
Two files are needed: the backup script and a file stating which files to include/exclude from the backup source.
The script is very simple; it rsyncs 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 include/exclude list.
Save it as
rbackup.sh and make it executable:
#!/bin/sh # rsync backup script sudo sh -c " rsync -av --delete-excluded --exclude-from=backup.lst / $1; date > $1/BACKUP "
- Backup source;
- In this case it's performing a backup on the whole root.
- Backup destination;
- Passed as an argument to the script; e.g.
- Include/exclude list;
- This example uses
As deciding which files should populate this list can be difficult, here's a typical backup example that excludes common files that do not need to be backed up, such as the vast majority of
/dev. Note that specifying every desired file or directory in
Include is not needed; this section only acts as a filter for statements in
Exclude. This file is in the traditional include/exclude rsync format.
Save the following as
# Include + /dev/console + /dev/initctl + /dev/null + /dev/zero # Exclude - /dev/* - /run/* - /proc/* - /sys/* - /tmp/* - lost+found/ - /media/* - /mnt/*
- Content in system directories;
/tmpare excluded because they are created by the system at runtime, while the directories themselves need to be preserved since they are not regenerated at boot. Lastly, all
lost+foundinstances are skipped since they are partition-specific. For Archlinux
/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. These files can be regenerated with
- Even though
/devis excluded, 4 files that are not dynamically created by udev need to be preserved. These are
/media/backup as appropriate, and mount the destination device:
# mount /dev/sdb1 /media/backup
Run the backup script (note that the trailing "
/" character is necessary):
# ./rbackup.sh /media/backup/
After the sync is finished, the backup destination's
/etc/fstab has to be modified, a boot loader needs to be installed on the backup destination, and configuration in the destination's
/boot/grub/menu.lst requires to reflect the new location.
Edit the backup destination's fstab:
$ nano /media/backup/etc/fstab
none /dev/pts devpts defaults 0 0 none /dev/shm tmpfs defaults 0 0 /dev/sda1 /boot ext4 defaults 0 1 /dev/sda5 /var ext4 defaults 0 1 /dev/sda6 /usr ext4 defaults 0 1 /dev/sda7 / ext4 defaults 0 1 /dev/sda8 /home ext4 defaults 0 1 /dev/sda9 swap swap defaults 0 0
Because rsync has performed a recursive copy of the entire root filesystem, all of the
sda mounpoints are problematic and will cause the backup boot to fail. In this example, all of the offending entries are replaced with a single one:
$ nano /media/backup/etc/fstab
none /dev/pts devpts defaults 0 0 none /dev/shm tmpfs defaults 0 0 /dev/sdb1 / ext4 defaults 0 1
As before, remember to use the proper device name and filesystem type.
Open the GRUB console:
Direct the install towards the destination device:
root (hd1,0) setup (hd1)
- This should point to where the GRUB files are located--in this case, "
hd 1" means the second storage device (
/dev/sdb) and "
0" is the first partition (
- The command specifies where the actual boot loader is to be installed. In this example it is installed to the MBR of the second storage device.
The problem here is that even though the boot loader installs correctly, its menu entries are for the main system's partitions, not the backup system's.
It's possible to fix this by creating a custom
/boot/grub/menu.lst for the backup destination. In order to do this, modify
rbackup.sh so that it copies a custom
#!/bin/sh # rsync backup script su -c sh -c " rsync -av --delete-excluded --exclude-from=backup.lst / $1; cp ~/custom.menu.lst $1/boot/grub/menu.lst; touch $1/BACKUP "
menu.lstwith a custom version solely for the backup, add a new GRUB entry pointing to the backup device or simply edit GRUB's menu during boot time.