Choosing a tape backup drive can be a simple job if you need to back up a single standalone system with a relatively small hard drive. The decision becomes more complex if the system has a larger hard drive or if you must back up a desktop system as well as a laptop.

Choosing a tape backup drive type can be an even more complex program if you must back up a network server's hard drives and perhaps even back up the workstations from the server. As you ponder which backup tape drive you should select, consider the following factors:

• The amount of data you must back up

• The interfaces your equipment supports

• The data throughput you need

• The tape standard that is best for your needs

• The cost of the drive and tapes

• The capabilities and compatibility of the included driver and backup software

• Support for disaster recovery

By balancing the considerations of price, capacity, throughput, compatibility, and tape standard, you can find a tape drive that best meets your needs.

Capacity

The first rule for selecting a tape backup drive is to buy a drive with a capacity large enough for your needs, both now and for the foreseeable future. The ideal is to buy a drive with enough capacity so you can start your backup software, insert a blank tape in the drive, walk away from the system, and find the backup completed when you return.

Because tape backups are generally rated by their maximum (2:1 compression) capacities—which is seldom reached in practice—you should calculate the "true" size of a tape backup drive by multiplying the native (noncompressed) capacity of a drive by 1.5 (equal to rating the drive as 1.5:1 compression).

Thus, a so-called "20GB" tape backup might be better described as having a "15GB" capacity (10GB uncompressed times 1.5). Of course, the compressed capacity of a drive depends on the backup software you use, the settings you use, and the type of data you back up.

Already compressed data, such as JPEG and GIF and some types of TIFF graphics files, can't be compressed further, whereas text and database files can be compressed significantly. If you find that you have higher or lower compression ratios during backup, use the compression ratio you normally achieve to help estimate your true backup capacity.

You should always ensure that your tape backup medium supports a capacity larger than your largest single drive or partition. This makes automated backups possible because you won't have to change a tape in the middle of a backup.

And, even if you don't mind replacing tapes in the middle of a backup, a single-tape backup is safer. If the first tape of a multiple-tape backup is damaged or lost, the entire backup is unusable with most backup systems!

Tape Standards and Compatibility

The next most important consideration, after adequate capacity, is choosing a drive whose tapes meet a standard that is useful to you. If you have existing tapes you want to restore, or you receive tapes from other users that you must read, you need a drive that can work with those tapes.

Use the backward-compatibility information listed earlier to help you decide on a drive to purchase if this feature is important to you. If your ability to work with older tape media is only an occasional issue, you might prefer to buy a high-performance drive for current backups and maintain an older drive that matches the older standard.

Software Compatibility

Equally important to your consideration is the software required to operate each drive. Currently, most parallel port and ATA drives come with software that runs under Windows operating system versions from 98 to XP. SCSI tape drives usually also support Windows NT, Windows 2000/XP, or Unix.

USB-based drives are primarily designed for Windows 98/Me/2000/XP, although Windows 2000/XP might not support as many devices as Windows 9x/Me does. Check the manufacturers' Web sites for operating system compliance if your office's computers use more than one operating system.

Most operating systems have their own software for backing up data to a tape drive. If you intend to use this software, you should verify that the drive you purchase is supported by each piece of software on each system you intend to use with the drive. Third-party programs usually offer more features, but you might need to buy separate programs for the various operating systems your office uses.

Data Throughput

Any of the ATA, IEEE-1394a, or SCSI interface drives covered earlier should provide adequate performance (1MBps or above when backing up compressed data), but performance suffers if you opt for the convenience of USB or parallel port drives. Floppy-interface QIC, QIC-Wide, and Travan drives should be considered obsolete for large-drive backups because of the limitations of the floppy interface and their small capacities.

Cost

You can figure the cost per MB for a drive in two ways: media cost only (which is valid for users with an existing drive) or drive plus media costs (which is a better method for new purchasers). Regardless of your favorite choice(s) in removable storage, be sure to look at the total picture, taking into account the savings from multipack data and the benefits of the extra speed of SCSI and ATA.

Support for Disaster Recovery

Disaster recovery, which enables you to create a tape backup and floppy disk set that can be used to reinstall an entire operating system and data file set without installing Windows first, is a function of both the backup software and the drive interface.

Disaster recovery is supported with most backup programs, but drives that connect to the USB or IEEE-1394a interfaces cannot support disaster recovery because they use Windows drivers. Because a disaster recovery data restore process starts in the MS-DOS mode, these drives can't be accessed because DOS lacks drivers for these ports.