Difference between revisions of "User:Gen2ly/System backup and reinstall"

Revision as of 13:53, 13 June 2012

This article is intended to show you how to backup your configurations and your package list, then to do a full system restore, restore packages, and finally restore your configurations..

Motivation

The need for this documentation is uncommon in the sense that the need to restore from configurations only is only really necessary for the following reasons:

1. You would like to change your system architecture (e.g. 32bit to 64bit).
2. If a program or programs begin to behave unexpectedly and no help in the forums (or elsewhere) is available is able to fix the problem. By chance reinstalling your programs and other configurations might fix the problem.
3. You have limited hard disk space and are not capable of doing a full restore from backup.

Backup

Using tar in a script can make archiving configurations get done in just a couple steps.

Include and Exclude Files

Tar has the ability to read from both an include and an exclude file. This means that you can tell tar everything you would like to include in the backup and exclude just by using two files. The format used is one line per file or directory that indicates the full path. For example:

/etc/pacman.conf
/etc/rc.conf
/home/user
...

And is invoked like this:

tar --files-from=include.txt --exclude-from=exclude.txt -c --xz -f backupname.tar.xz

The name of the files can be anything you want. The exclude file is like the include file but additionally has the ability to be able to use regexps, as well as being able to be commented and have blank lines.

Backup Script

This backup script has the ability to add to the include and exclude files and the ability to backup the configurations. The usage is:

 bckcfg <i|e|n|c> - backup configurations
  i - add to the include list a file or folder
  e - add to the exclude list a file or folder or regexp pattern
  n - add note
  c - create backup

For example to add to the include file:

bckcfg i /etc/rc.conf

And to add to the exclude file:

bckcfg e .thumbnails/

The script is able to detect the full path so writing a relative or partial path is acceptable.

To backup, this script names your backup by several definable variables, removes old backups if desired, then backs up the configurations. The include and exclude files are placed in the same directory as the backup script.

bckcfg

#!/bin/bash
# Backup configurations

# Backup destination directory
#bckp_dest="/home/todd/Desktop"
bckp_dest="/run/media/todd/Backup/backup-configs"

# Backup name
comp="${HOSTNAME}"  # Computer name
dist="arch"         # Distro
type="configs"
date="$(date "+%F")"
bckp_file="$bckp_dest/$comp-$dist-$type-$date.tar.xz"

# Include and exclude file locations
scrpt_dir="/home/todd/.scripts/backup"
incl_file="$scrpt_dir"/${0##*/}-inc.txt
excl_file="$scrpt_dir"/${0##*/}-exc.txt
note_file="$scrpt_dir"/${0##*/}-nte.txt

scrp_help () {
echo " ${0##*/} <i|e|n|c> - backup configurations
  i - add to the include list a file or folder
  e - add to the exclude list a file or folder or regexp pattern
  n - add note
  c - create backup"
}

del_old_bckps () {
if [[ -n "$(find "$bckp_dest" -mtime +30)" ]]; then
  find "$bckp_dest" -name "$distro-$type-*" -mtime +30 -exec rm {} \
  \; && echo " Deleted backups older than one month."
fi
}

case $1 in
  # Add to include list file or folder
  i ) shift
      for f in "$@"; do
        # Check if selection(s) exist
        if [ ! -e "$f" ]; then
          echo " File \""$f"\" does not exist."
          continue
        fi
        # Append file/folder to include list
        full_path=$(readlink -f "$f")
        echo "$full_path" >> "$incl_file" && \
        echo " Added \""$f"\" to ${0##*/} include file."
      done
      # Sort entries
      sort -u "$incl_file" -o "$incl_file" ;;
  # Add to exclude list file, folder, or regexp pattern
  e ) shift
      echo " * \"${0##*/}\" doesn't check if patch is correct because the exclude file can contain regexps.  Be sure the path is correct (e.g. '/mnt/win/*')" | fmt -c -u -w 80
      read -p " Add \""$@"\" to ${0##*/} exclude file? (y/n): " add_exclude
      if [[ "$add_exclude" == [Yy] ]]; then
        echo "$@" >> "$excl_file" && \
        echo " Added \""$@"\" to ${0##*/} exclude file."
      else
        echo " Error: \""$@"\" not added."
      fi ;;
  # Add to note file
  n ) shift
      echo ""$date"-"$(date "+%r")": "$@"" >> "$note_file" && \
      echo " Added string to \""$note_file"\"." ;;
  # Create backup
  c ) # Check if backup directory exists
      if [ ! -d "$bckp_dest" ]; then
        echo " Directory \""$bckp_dest"\" does not exist."
        exit
      fi
      # Delete old backups
      #del_old_bckps
      # Backup configurations
      sudo tar --exclude-from=$excl_file --files-from=$incl_file -c --xz -f $bckp_file ;;
  * ) # Display usage if no parameters give
      scrp_help ;;
esac

Packages

Package lists can be created that can re-install your programs upon a restore. If you have the hard disk space available, you might also want to consider saving the install packages (*.pkg.tar.gz) as well.

Creating a Package List

You can create a list of all installed official packages with:

pacman -Qqe | grep -v "$(pacman -Qqm)" > pkglist-off.txt

This will create a list of all packages in the official, enabled pacman repositories (i.e. core, extra, community and testing).

To create a list of all local packages (includes packages installed from the AUR):

pacman -Qqm > pkglist-loc.txt

Saving Package Tarballs

Pacman saves all package tarballs in /var/cache/pacman/pkg/. Saving these will increase your re-install speed so consider saving these as well. You might want to think about reducing the size of the cache before backing up too. Pacman has the ability to remove any uninstalled packages from the cache with:

pacman -Sc

Yaourt

If you use Yaourt to install packages from the AUR, you might want to consider setting up a cache for it (Yaourt by default does not save the built package tarballs). To setup a cache directory, edit /etc/yaourtrc to include one:

  ExportToLocalRepository /var/cache/pacman/pkg-local

Then give the directory the necessary permissions so Yaourt can write to it as a regular user:

mkdir -p /var/cache/pacman/pkg-local
chmod 766 /var/cache/pacman/pkg-local

Copy these packages to your seperate medium.

Storing the Backup

After you have made up your tarred configurations, package lists, and (optionally) your install packages, you are going to need to store them on a seperate medium than your install partition/drive. Do not put your package lists and install packages in your tarred configurations. This is because all packages must be reinstalled first before you restore your configurations to prevent file conflicts (pacman will not install packages with file conflicts). If you have large enough USB Flash Drive these work well. Optionally you can burn them to a CD or use a partition utility like gparted to create an extra partition. If using CD's you can span large archives by using the split utility. To create a new partition consider using the Parted Magic CD which has gparted on it.

Restoring

Restoring will involve:

1. Installing the base system through the AIF (Arch Installation Framework).
2. Changing root.
3. Reinstalling all your packages.
4. Extracting your configurations.
5. Adding a new user.

AIF Install

Install Arch Linux as you normally would through the AIF on the LiveCD.

Change Root

When finished, mount your USB Flash Drive (or whatever medium you choose to save your configurations... on).

mkdir /backup-files
mount /dev/<disk-drive-parition> /backup-files

Your Arch install will already be mounted on /mnt so now copy these files to your Arch install:

mkdir -p /mnt/opt/restore
cd /backup-files
cp -a * /mnt/opt/restore

Now you will need to chroot (Change Root) to your Arch install:

cd /mnt
cp /etc/resolv.conf /mnt/etc
mount -t proc none /mnt/arch/proc
mount -t sysfs none /mnt/arch/sys
mount -o bind /dev /mnt/arch/dev
chroot . /bin/bash

Reinstall your Packages

Reinstall packages from the official repositories, the AUR, and locally installed packages separately to better diagnose problems if they occur.

Official

First reinstall packages from the official repositories;

pacman -Sy
pacman -S --needed $(cat /opt/restore/pkglist-off.txt)

The AUR

Yaourt comes in handy here. To quickly install yaourt again:

wget http://aur.archlinux.org/packages/yaourt/yaourt.tar.gz
tar xvf yaourt.tar.gz && cd yaourt*
makepkg -s
pacman -U yaourt-*.pkg.tar.gz

Then to install AUR pakages from the list:

yaourt -S $(cat /opt/restore/pkglist-loc.txt | grep -vx "$(pacman -Qqm)")

grep -vx ... here is used to remove packages that are already installed. This comes in useful in case you have to restart the command because you had trouble installing one of the packages. If you have packages already built by yaourt and in your yaourt cache, you can avoid recompiling again by going to that cache and installing the packages manually (pacman -U ...).

Extract Configurations

Once all packages have been installed you can extract the configurations:

tar xvf /opt/restore/hostname-arch-configs-date-tar.gz -C /mnt

A couple things to look out for:

• Be aware of any changes to your partition layout. If you changed your partition, you will need to edit both /etc/fstab and /boot/grub/menu.lst.
• If you had special options for the kernel ram disk (initrd), then you will have to re-compile it before your reboot to get your expected behavior.

Final Details

Good time to add your user now before you reboot. When creating a user, consider giving the user a unique user id (UID). This will help prevent conflicts in the future with other users and programs having the same UID (UIDs for users generally start at 1000):

useradd -m -u 1050 -G audio,optical,power,storage,users,video -s /bin/bash user

If you have restored a user home directory (/home/user) from your backup configurations, the -m switch will give a warning about an already existing home directory but will not alter the directory. Do not forget to change permissions in your home directory if your UIDs differ:

chown -R username:users /home/user

Now, reboot. Expect a few unexpected things here. No re-install is perfect. ALSA may pop up a warning and may have to be configure again and there may be a few other things unconsidered. That's it. Congratulations on your reinstall.