I USE TAPE to back up my system. I hate it.
Tape is fussy. Tape is slow. Tape backups have an uncanny talent for failing when the chips are down. Retrieving data from tapes can be tricky, since tape drives are typically invisible to standard system software and accessible only with second-rate backup programs that cannot read data they did not create. Although tapes produced on one drive should theoretically be usable on any compatible model, even that is not always the case.
Tape has two saving graces: It is cheap, if you consider time and frustration irrelevant, and it is capacious. The industry marches on with ever cheaper cartridges and drives to match the ever larger capacities of hard drives. One cartridge can now store gigabytes of data in a tiny case holding 750 feet of tape 8 mm wide.
Cartridges are labeled more honestly than the drives that use them. Drives using 1.6 megabyte tapes often call themselves 3.2-gigabyte units. The idea is that they can hold that much if the data can be compressed to fit in half its normal space, a feat that cannot always be achieved.
The Iomega Corp.'s Ditto Easy 3200, a drive I recently tested, uses so-called Travan tapes that hold up to 1.6 gigabytes of uncompressed data and cost about $40. It can also read tapes produced in most of the smaller Travan and QIC formats, and write to some of them. An internal model costs about $250 and connects to an accelerator card you must install inside your computer. I tried the $300 external unit, which hooks up to a parallel port, which for full performance must be bidirectional. The drive has a port for reconnecting the printer but not an on-off switch.
Cleaning the tape head is recommended after approximately 24 hours of operation. You can do it with a special cleaning cartridge or with a cotton swab moistened in "pharmaceutical grade isopropyl alcohol." Read the manual carefully; depending on which Ditto model you use, you must wipe either "across the head" or "up and down [not sideways]." Insufficient cleanliness may lead to data errors.
Is there any other common storage medium whose backup programs make you choose between safety and speed? Is there any other medium that, as Iomega's on-screen manual blithely warns, occasionally "will de-spool, or become unattached from one of the spindles?" Good advice: "If a tape de-spools during a restore procedure, do not try to repair it yourself. In the process, you will probably damage or destroy the data." Welcome to the world of tape.
It is a lackadaisical, leisurely sort of world. Though transferring 1,784 files with 191 megabytes of data from a hard drive to one of Iomega's removable Jaz drives took just over four minutes, the same job took more than 18 minutes with tape, not to mention another 35 to make sure that the tape's data actually matched the drive's. That added step is not mandatory, but you omit it at your peril. As the manual warns, "Even though data verification takes longer, it is strongly recommended that you use data verification to help ensure the reliability of your backups."
When you factor in tape's sluggishness and uncertainty, costlier backup media like recordable CD-ROMs, magneto-optical disks and removable hard drives begin to look like bargains.