376 Technique 49: Getting Ready to Back Up Your Data

Choosing an Archive Program

Many archiving programs are available for backing up Linux computers. Here are a few that you should consider:

AMANDA (Advanced Maryland Automatic Network Disk Archiver): This suite of tools is designed to archive entire networks. With

AMANDA, you create a single “backup server,” and from there, you can archive any computer that you can reach over the network. You

can even use AMANDA to back up Windowsbased computers. You can find AMANDA at www.amanda.org.

Arkeia Light: Arkeia is another network-enabled backup tool. You can find it at www.arkeia.org. The free version is missing a few features that are included in the commercial program, but Arkeia Light is still a very useable tool with a nice-looking user interface. One of the big advantages to Arkeia (the commercial version) is that you can talk to a support person if something goes wrong (a service you don’t get with opensource tools).

Bacula: A relatively recent addition to the opensource archive arena, Bacula has some heavyduty features that you may need in a large organization. Bacula keeps a complete history of

all archive operations in a relational database (SQLLite, PostgreSQL, or MySQL), which makes it quick and easy for you to find the archive volume that contains the data that you’re interested in. And, because the history is stored in a database, you can create custom tools and custom reports from the archive history tables.

Bacula lives at www.bacula.org. Its motto is “It comes by night and sucks the vital essence from your computers” — how could you resist a tool like that?

Mondo: Mondo is not really an archive program as such — it’s a rescue tool. After you build a bootable Mondo rescue disk, you can restore your entire operating system without reinstalling everything from scratch. Combine Mondo with a complete backup plan, and you’ll recover from hardware failures much faster. You can find more information about Mondo at www.microwerks. net/~hugo.

tar: Short for tape archiver, tar is the longrunning standard for backup. It’s versatile, flexible, and reasonably easy to use. It’s also available on every Linux (or UNIX) computer you’re likely to encounter (it’s even available on many Windows systems). In the next technique, we show you how to use tar (together with a helper tool named cdbackup) to create multidisc backup sets on CDs or DVDs.

50 Backing Up

Your Data

Technique

Save Time By

Estimating how much media you’ll need for your backup

Taking interim backups of the directories that are most likely to be lost

Using incremental or differential backup schemes

Using tar and cdbackup to make backup CDs

Backing up data may mean backing up a single file, a directory tree, or an entire system. You may choose to do incremental backups, differential backups, or full backups depending on the amount of

data you need to store and the value of that data (see Technique 49 for details on the different backup types). One way or the other, you’ll be using an archiving program.

tar is a simple but flexible tool that creates sturdy, portable archives. You can use tar to create archives quickly and easily, and you can write those archives straight onto your hard drive or onto other devices. You can use tar to bundle files into archives, and move them easily and quickly to CDs or thumb drives or across your network.

Performing interim backups of important directories that might be lost through user error (such as home directories and e-mail files) can save you from restoring from a system backup just to extract a single file.

tar won’t write straight to CD without a helper application — it’s great with tape drives, but it’s not so hot with CDs. We’ve found a great helper tool called cdbackup that we show you how to use in this technique. cdbackup works with tar to create archives that can span multiple CDs (or DVDs).

In this technique, we show you some useful variations on the tar command and give you a step-by-step introduction to differential and incremental backup schemes. Remember, backing up means never having to say you’re sorry.

Estimating Your Media Needs

It’s nice to know how much media you’ll need before you start a backup. You don’t want to get halfway through and find out that you need to run to Office Depot to pick up more tapes. It’s also nice to know your archive size if you’re planning on carrying it with you on a thumb drive or other removable media.