372 Technique 49: Getting Ready to Back Up Your Data

you some factors to consider to help you choose the right media, archiving scheme, and archive type.

Deciding What to Archive

When you consider putting together a backup plan, your first instinct might be to back up everything. That way, if anything goes wrong you can get your data back quickly. But consider how much media you would need to archive your entire system. These days, it’s not uncommon to find notebook computers with 60GB hard drives. Given that a CD holds only 660MB (or 0.66GB), you would need 100 discs to back up the whole drive. (Actually, you would need fewer than that if you use compression.) You wouldn’t want to back up your system very often at that rate.

Instead, back up only data that you can’t easily reproduce. You know that you can reinstall Linux on your computer without too much hassle. You can reinstall all the RPM packages and other software that you’ve loaded. And you certainly don’t need old log files and temporary files. That narrows your backup requirements considerably.

So what should you archive? Basically, anything that you’ve created or modified, including the following:

Configuration files

User home directories

E-mail (if you store e-mail on your computer rather than at your ISP)

Software (or other projects) that you’ve developed

Choosing Archive Media

Choosing an archive media type is a matter of finding a balance among the following factors: the cost of the backup device and media, the speed and ease of use,

and how much data the media can hold. The value of your data should definitely impact your choice as well. Here are several media types to consider:

Tape drives

Removable disks (SCSI drives or external hard drives)

Removable non-optical media (Jaz and Zip drives)

Removable optical media (CDs and DVDs)

Online storage services

The size and configuration of your system influences the requirements of your backup scheme. Good backup media for one system isn’t necessarily a good choice for another.

Making the trade

When putting together a backup plan, a major trade-off to consider is recovery time versus the amount of media you need. If you’re a small network or single computer user, you can choose to back up only the things you can’t replace — e-mail files, data files, high score files for your favorite games, and so on. On the other hand, if you archive data and programs, you won’t have to reinstall (and reconfigure) all of the programs you already have on your system.

Tape drives

A tape drive is a good choice for backing up large systems. In fact, a tape drive is often the only practical choice if you have a lot of data to archive. Many consumer and business tape drives are available with a wide range of prices and capacities. Tape drives can be either internal or external, and they come in a variety of formats. You can choose from dozens of drive manufacturers.

The biggest advantage of a tape backup scheme is the storage capacity. Depending on the tape drive, the contents of a complete system can easily be archived onto a single tape. Tape media is also very affordable, so keeping archived backups generally

Choosing Archive Media 373

isn’t a problem. The biggest investment is in the tape drive itself.

Tape drives can range in price from hundreds to thousands of dollars, depending on the backup capacity. Although the drive might be expensive, the media is affordable, making it feasible to archive backups.

One disadvantage of using tape backup is the relatively high failure rate compared to other media types. Tape drives also tend to be slower than other backup types. For a large system, they can be a good choice, but for a small system, you might want to consider other options.

Removable and external disk drives

If you’re backing up a single machine, removable or external hard disks are good options to consider. They’re fast and dependable, and the prices are dropping almost daily. With an external FireWire drive, you can back up an entire computer in minutes.

FireWire is a very fast hardware protocol. If your system supports FireWire, look for FireWire-enabled devices to save time.

Removable hard drives are drives that fit into a slot on your computer. Plug one in, and you’ve got an extra drive that you can use to hold archived data. Unplug it and store it someplace safe so you’ll have a backup if you need it.

Removable hard drives are too expensive for most people to use for archiving backups; buying a bunch of hard drives to store would add up fast. They are also more fragile than other media — jostling a removable drive in and out of the slot doesn’t help its longevity. Still, for backing up a small system, removable hard drives can be a good choice.

External drives are a better choice for many people than removable hard drives. They’re sturdier, and because the connection is made with a cable instead of a slot, the chance of damaging the drive in the

process of connecting it is minimal. External drives hold a good amount of data and are very affordable. With a FireWire interface, they’re also fast. Many external drives offer both FireWire and USB connections for more flexibility.

Depending on your system, you can also use a FireWire external drive as an alternate boot disk.

Flash drives, SD memory cards, CompactFlash, and other removable media types also deserve mention. They’re little, but they’re really handy if you just need to back up a small amount of data.

Use a flash drive as a backup container for your passwords. Make copies of your ~/.gnupg directory and ~/.ssh directories, as well as encrypted text files containing other passwords you need often. Now, you can easily take your passwords and keys with you when you travel.

Be sure to encrypt cleartext password files and your private keys in case you lose the flash drive.

Removable media

A Zip drive is like a floppy drive on steroids. It can hold a good amount of data, it’s easy to store off-site, and it’s portable and network friendly.

A Zip drive can be either internal or external (Iomega even has an external FireWire available), and the media itself is rugged and portable. The largest Zip drive currently holds 750MB — that’s a little bit more than a CD.

Zip disks are more expensive than blank CDs or DVDs, and most systems now come with a CD or DVD writer. On the upside, Zip drives have two main advantages:

Writing data to a Zip drive is much faster than writing to a CD or DVD, and a Zip drive is inherently rewritable (it’s just a disk drive). Zip disks are about as durable as CDs.