Tech Tutorial: 206.2 Backup Operations #

Introduction #

Backup operations are a crucial aspect of system administration to ensure data safety and recovery in case of hardware failure, data corruption, or accidental deletion. This tutorial will cover key utilities and methodologies for performing backups on Linux systems, aligning with the LPIC-2 exam objective 206.2.

Key Knowledge Areas #

Awareness of backup media and filesystems suitable for backups
Knowledge of backup utilities
Understanding of backup strategies

Utilities #

tar
dump
restore
rsync
dd
mt
mtx
bzip2
gzip
xz

Step-by-Step Guide #

1. Using `tar` for Backups #

The tar command is used to create archives and is a standard method for backups.

Detailed Code Examples #

Creating a tar archive:
```
tar cvf backup.tar /home/user
```
This command creates (c) an archive file (backup.tar) containing the /home/user directory, displaying the progress (v), and using a file as output (f).
Extracting a tar archive:
```
tar xvf backup.tar
```
This extracts files from backup.tar with verbose output.
Creating a compressed tar archive using gzip:
```
tar czvf backup.tar.gz /home/user
```
Creating a compressed tar archive using bzip2:
```
tar cjvf backup.tar.bz2 /home/user
```
Creating a compressed tar archive using xz:
```
tar cJvf backup.tar.xz /home/user
```

2. Backup and Restore Using `dump` and `restore` #

dump and restore are utilities specifically designed for backup and recovery of ext2/ext3/ext4 filesystems.

Performing a full backup with dump:
```
dump -0u -f /mnt/backup/home.dmp /home
```
-0u tells dump to perform a level 0 (full) backup and update the dump date. -f specifies the output file.
Restoring a backup:
```
restore -rf /mnt/backup/home.dmp
```
This restores files from the home.dmp dump file.

3. Incremental Backups and Synchronization with `rsync` #

rsync is powerful for both backing up and synchronizing data.

Basic rsync backup:
```
rsync -av /home/user /backup/user
```
-a stands for archive mode, and -v gives verbose output.

Rsync over SSH:

rsync -avz -e ssh /home/user user@remotehost:/remote/backup

-z enables compression.

4. Using `dd` for Low-Level Backups #

dd can be used for block-level backups, useful for whole disk or partition backups.

Creating a disk image:
```
dd if=/dev/sda of=/mnt/backup/sda.img
```
if is the input file (disk), and of is the output file (image).

5. Managing Tape Drives with `mt` and `mtx` #

Rewind a tape:
```
mt -f /dev/st0 rewind
```
Writing to a tape with tar:
```
tar cvf /dev/st0 /home/user
```

Loading and unloading tapes with mtx:

mtx -f /dev/sg0 load 0
mtx -f /dev/sg0 unload 0

Conclusion #

Understanding and utilizing these backup utilities and strategies will enhance your ability to protect data and recover from data loss. Regular backups and the right tools are fundamental to maintaining the integrity and availability of data in a Linux environment. Tailor your backup strategy to fit the specific needs of your systems and data to ensure optimal protection.