Does your small business have a comprehensive backup plan in place? It better. One nasty computer crash—or even one busted water pipe—and a small business without the means to restore mission-critical data could be out of commission for days, even weeks. If you haven't formulated a backup plan yet, now is the time to do so. To help you along, this guide can show you ways to back up that are both cost-effective and efficient.

For years, backing up data to tape has been the standard for most businesses, largely because of tape's reliability, capacity, and cost. But the storage landscape is changing. CDs, DVDs, and removable hard drives are proliferating. A number of sites now provide automatic data backup services on the Internet. And then there's the relatively new technology known as disk-to-disk (or D2D) backup. Determining which backup method best fits your needs means first having a good sense for the size of the files you want to store, as well as your purpose for storing them.

Consider the following backup methods:

• Tape. The oldest and generally least expensive storage option, tape drives come in several types and sizes. The most commonly used tape drives are DLT (Digital Linear Tape), LTO (Linear Tape Open), and AIT (Advanced Intelligent Tape). Storage capacities range up to 200 GB, with a media cost of about a penny to 5 cents per megabyte. The biggest drawback to tape is that data recovery is slow. Tape isn't a random access media, which means that instead of being able to pinpoint the data you want to access instantly (the way you can with other media), you have to wind through the tape sequentially to locate it. Plus, maintaining multiple sets of tapes in a tape library can be problematic.

• CD and DVD. Most current PCs have a CD-RW drive that can store 700 MB of data on a write-once CD-Recordable or 530 MB on a CD-Rewritable. While many users have flocked to speedy, reliable CD-R media, questions have arisen about the slower (and sometimes more error-prone) CD-RW disks. Still, this is an inexpensive and convenient form of storage, with CD-R disks selling for about 50 cents and CD-RW disks for about $1.25. Rewritable DVD drives, meanwhile, let you store up to 4.7 GB on a single disc—nearly seven times the amount of data that fits on a single CD-R/RW. Like CD-RW drives, rewritable DVD drives support both write-once and rewritable media. Interest in these drives has skyrocketed lately—and it's no wonder. The average price of a drive has dropped by more than half in the last two years, to about $300, and prices are expected to go even lower.

• Removable drives. A removable hard drive such as Iomega's Zip drive can store up to 750 MB of data. For many small business users, these devices, which sell for less than $200, provide sufficient storage capacity. (A good rule of thumb for removable media: choose a type that's large enough to hold one entire backup.) The major downside of removable hard drives is the cost of the media—disks can run around $13. On the plus side, these drives can transfer data at a snappy 7 MB per second.

• Norton Ghost 2003. Another option to consider: You can back up a precise image of an entire drive's contents by using Norton Ghost 2003. This product enables you to create disk images and store them on network drives or on multiple types of media, including CD-R/RW and DVD/RW drives. When you restore a drive image, the contents remain exactly as they were when the image was made.

• Online backup. Over the last few years, a number of sites have emerged that will back up your data on the Internet. (Indeed, many of these offerings were designed specifically for small businesses.) Typically, users are charged a fixed subscription fee per month for a specific amount of storage. The first backup usually takes a long time, but after that the program updates only files you've changed since the last backup, so the process goes much faster. (Still, experts recommend that you have a broadband connection.) Two important points to consider with online backup: be sure that the amount of storage provided is enough to back up all your files, and that the service you choose has backup and redundant systems.

• Disk to disk. The idea behind D2D is that new, inexpensive ATA (Advanced Technology Attached) disk "arrays" are used as the primary storage medium for a backup and recovery system. Instead of going to tape, the initial backup goes directly to disk and only later is sent to tape for long-term, off-site archiving. D2D proponents argue that while tape is still a tried and true method for accomplishing the disaster recovery and archival purposes of backups, restoring recently damaged files or systems is better handled by disk. Why? Because restoring data from disk is much faster. Supporters also argue that copying from disk to tape is faster than copying from tape to tape. Plus, unlike tape, disk storage can be constantly monitored for failure—making it more reliable. With prices ranging from $8,000 to $10,000 per terabyte, ATA disk arrays are looking like an attractive option. Bottom line: Tape is still tops because of cost, but D2D's speed and competitive pricing are narrowing the gap.

Testing, testing
Whichever backup method you choose, conduct monthly tests of your entire system to be sure you can recover data when you need to. The unaffordable cost of downtime to your business demands it.