Old Style Of Backup Systems

tapedriveBack in the day when data backup only consisted of kilobytes, the backup systems were much more rudimentary.  Who remembers tape drives?  Seems like a relic of the past, right?  Well, it wasn’t so long ago that tape drives were the latest and greatest, costing thousands of dollars.  This excerpt from an article from 1987 highlights just how far we have come in terms of data storage.  A simple smartphone that we now take for granted would have been unthinkable back in 1987.

Tape cartridges in 1/4-inch format, most common for microcomputers, also come for 3 1/2-inch and 5 1/4-inch start-stop, streaming and floppy-like drive units.

Start-stop devices record and access best in file-to-file mode. Streaming units are good at image backup, and floppy-like devices eliminate the need for a separate tape controller but require a formatting procedure that takes 40 minutes or so.

Many microcomputer installations need access to mainframe-resident data. They often resort to traditional 1/2-inch reel-to-reel magnetic tape systems. However ungainly and costly these devices may be, they transfer data efficiently between mainframe and microcomputer. Costs are in the $3,500 range.

The reel-to-reel units dwarf a standard desktop system, and there are few alternatives. However, with growing acceptance of IBM’s 3480 tape cartridge, the same standard of interchangeability that now applies only to tape reels may become available in a smaller configuration.

Vendors are working to supply a 5 1/4-inch drive form factor. The 1/2-inch cartridge is expected to be available by the end of August, with interfaces for small systems.

Initially aimed at super-microcomputers, these drives eventually will provide capacity between 250M and 300M for traditional microcomputers. The switch will give microcomputers a more cost-effective way to take advantage of the volumes of data generated by mainframes.

In the meantime, the 1/4-inch tape DC600-style cartridge is used by microcomputers. Widely available in the 5 1/4-inch form factor, 1/4-inch cartridge drives have become a primary source of backup.

DC2000-type drives, growing in popularity because of their smaller size, adapt to the space constraints of the desktop. Measuring 3 1/4 by 2 1/2 by 3/8-inches, about the size of the familiar audio cassette, these miniature cartridges squeeze 40M onto a 20-foot piece of 1/4-inch magnetic tape. Data is written onto 20 or 24 tracks positioned across the width of the tape.

Depending on whether they adhere to QIC-100 or QIC-40 standard specifications, these drives use a floppy disk interface to transfer data at floppy speeds, or they connect to a dedicated interface that allows faster transfer.

Different Interfaces

So-called floppy tape devices run the tape drive as if it were a DOS disk and operate from the floppy disk interface within the microcomputer.

In the 10M to 20M capacity range, DC1000 catridges, although about the same size as the DC2000, record on .15-inch tape. When used through the system’s floppy disk controller, they are the lowest-cost alternative with sufficient capacity to handle most low-end backup storage needs.

For users who must move data between microcomputers and larger but dissimilar computer systems, it is necessary to go to a network or put the data on a floppy and walk it between systems, according to Larry Hemmerick, director of planning for Cipher Data, San Diego. If volume storage or volume data is involved, the user often must resort to nine-track tape.

For PC applications that absolutely must be interchangeable with host systems, a nine-track tape is the solution. It is expensive but interchangeable.

Because the microcomputer environment has no tape tradition, there is no recognized procedure for performing backup. According to industry pundits, “There are only two types of people in this business: Those who have lost data and those who are going to.”

Two factors make or break tape backup: speed and ease of use. Software affects both. On the issue of data security, the amount of time to restore data to the system is irrelevant because, no matter how long it takes, that time is less than the time needed to rebuild an entire crashed disk.

A user who buys a 1/4-inch drive should realize that its performance is less than that of a reel-to-reel drive, with a price differential of $2,000 compared with $50,000. Backup time, throughput, error detection and correction capability are not equivalent. The 1/4-inch works, it just doesn’t work as well.

Rotating media devices offer a better, though more expensive, solution where data protection is important. Fast restoration of data also is essential after system failure or when on-line access to stored data is a benefit.

Disk drives access data faster than tape because their moving read/write heads minimize the distance traveled on the disk surface. Tape devices, on the other hand, have a fixed head past which the tape moves to reach the desired location. Even at 90 inches per second, it takes some time to move 200 to 600 feet of tape.

Although integrating rigid cartridge products into a system is more expensive than using tape products, it is the only way to provide functions beyond backup, according to Tom Desmet, director of product planning for Magna Computer Corp., Manchester, N.H.

A removable Winchester disk allows the user to remove the data and put it in a secure environment. Because encryption and password protection can be provided on the cartridge, the disk will be unusable on any other machine or by anyone lacking the password.”

Killmon, Peg. “Micro storage devices; newer storage devices do more than back up data.” Government Computer News 28 Aug. 1987: 89+.

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