Backing Up Over Networks
After you have backed up your files and gathered them into a tar archive, what do you do with that archive? The primary reason for having a backup is in case something happens (such as a hard disk crash) where you need to restore files from that backup. Methods you can employ to keep those backups safe include:
❑ Copying backups to removable media such as tape, CD, or DVD
❑ Copying them to another machine over a network
Fast and reliable networks, inexpensive high-capacity hard disks, and the security that comes with moving your data off-site have all made network backups a popular practice.
For an individual backing up personal data or a small office, combining a few simple commands may be all you need to create efficient and secure backups. This approach represents a direct application of the UNIX philosophy: joining together simple programs that do one thing to get a more complex job done.
Although just about any command that can copy files over a network can be used to move your backup data to a remote machine, some utilities are especially good for the job. Using OpenSSH tools such as ssh and scp, you can set up secure passwordless transfers of backup archives and encrypted transmissions of those archives.
Tools such as the rsync command can save resources by backings up only files (or parts of files) that have changed since the previous backup. With tools such as unison, you can back up files over a network from Windows, as well as Linux systems.
The following sections describe some of these techniques for backing up your data to other machines over a network.
NOTE: A similar tool that might interest you is the rsnapshot command (yum install rsnapshot). The rsnapshot command (www.rsnapshot.org/) can work with rsync to make configurable hourly, daily, weekly, or monthly snapshots of a file system. It uses hard links to keep a snapshot of a file system, which it can then sync with changed files.
Install this tool with the following commands:
$ sudo apt-get install rsnapshot
$ sudo apt-get install sshfs