For Business Preservation [ldots] Get It On Tape.

This article is the first in a two-part series. The second part will appear in the May issue of CTR.

Magnetic tape has been meeting our storage needs since the earliest commercial computers were introduced in 1950. As tape and other storage technologies evolved, a "storage blueprint" emerged. Offering high capacity and an exceptionally low storage cost, tape became the traditional backup and offline storage medium. The steady and sometimes breakthrough advancements in performance and capacity have helped tape maintain its leadership in the backup arena for decades.

With the coatings that are now a part of tape manufacturing, even the longevity issue has been resolved. In earlier times, it was common practice to refresh reel tape because the magnetically encoded information would "print through" to adjacent wraps of tape. This argument is still sometimes used against tape technology by those promoting other alternatives; however, with the coatings, it is considered a non-issue, so information can basically be stored indefinitely on magnetic tape. Today, tape not only offers enhanced reliability, but it also provides the widest variety of form factor and recording format choices in the storage industry and remains unrivaled in terms of cost and capacity. With the advancements in hardware and media that are on the horizon, we can expect tape to continue playing a vital role in corporate data protection strategies well into the future.

The demand for low-cost tape solutions with higher capacities and faster transfer rates is being driven by the fact that organizational storage requirements are growing exponentially while the window available for backup is shrinking. With the 24x7 availability of the Internet and the Web, an increasing number of corporate databases must be available around the clock and the cost of downtime has gone up.

Network compositions are also changing. Only a few short years ago, Local Area Networks were primarily simple systems that connected a few PCs together to enable sharing of data and peripherals. Now, network managers must include PCs with a minimum of 2GB of storage, remote work groups, servers with different platforms, and even laptops.

Multi-Player Market

According to IDC, the tape drive market achieved drive sales of $2.9 billion last year. For the most part, individuals, departments, and enterprises purchased backup solutions that have been around for some time (Fig 1)--DLT, half-inch, 4mm, etc. However, while each technology has its own well-established native capacity/transfer rate position, the marketplace is far from static. A number of new tape technologies are being developed to provide faster transfer rates, higher capacities, and increased reliability.

Some of the new tape formats that have entered the scene include:

* OnStream's Advanced Digital Recording (ADR) - It is a new variable-speed tape technology that is ideal for power desktop, servers, and workstation applications. ADR drives read and write eight tracks of data simultaneously.

* Ecrix - a unique technology that provides a very aggressive capacity and price point. With the manufacturer's partners, they have developed a sound automation strategy, which shows promise in a number of application areas.

* Benchmark - A DLT-based solution, the systems provide very good price, performance, and capacity. A number of automation manufacturers are launching products in this area.

* Linear Tape-Open (LTO)-based Ultrium drives -- They are designed to meet the capacity needs of network applications (See the article "Ultrium Reality Check" on p. 39 in the March issue of Computer Technology Review). LTO media will be available with 1st generation compressed capacities of 200GB.

Targeted Applications

Both the established and the new tape technologies are delivering solutions targeted at specific desktop, server, and enterprise applications (Fig 2). The most important factors to consider when selecting a tape backup option are the drive and its underlying technology. Important drive characteristics to consider are tape capacity, transfer speed, seek speed, and reliability. While most of these characteristics seem to impact performance, users need to understand that it's a combination of factors.

For example, a faster drive isn't always better. The CPU, bus, channel, interface, disk, and software overhead can dramatically impact performance. In many instances, fast tape drives have to frequently stop and wait, which can reduce the performance and drive reliability. Unless they are properly tuned, techniques such as parallel backup and striping can compound the drive performance problem.

File Recovery

Many organizations often feel that by using higher-capacity tapes, they will improve their overall backup and recovery performance; but according to a study by Strategic Research Corporation, the full capacity of a tape is seldom used. The analysts point out that 31 percent of the tape sets are 40MB or less and 79 percent are 80MB or less. In addition to being more expensive, the higher-capacity tapes require more search time to find specific files. This becomes an important issue, since 87 percent of all retrievals are for single files.

Disaster recovery seldom involves the rebuilding of an entire database or system. According to Contingency Planning Research, over 75 percent of the computer disasters were due to hardware, software, or user errors affecting individual files. Strategic Research notes that, typically, network managers run 17 single file restores a month. The typical restore requires 30 minutes and costs the organization thousands of dollars each year in labor and lost productivity. As a result, performance becomes a backup and recovery software consideration[ldots] not a tape drive issue.

DLT continues to be the leading tape backup technology for mid-sized networks. Owned by Quantum Corporation, it provided users with higher performance, faster throughput, and better reliability than early generations of DAT and 8mm drives. New generations of SuperDLT (SDLT) target 100GB native capacity per tape cartridge and 10MB/sec throughput.

Using a serpentine method of writing to the tape can double capacity and throughput. The data is written on tracks that span the length of the tape so that when the end of tape is reached, data is written in the track directly above and the tape is reversed. This eliminates the need to reposition the tape at BOT/EOT to record a new track.

DLT provides excellent reliability with more than 15,000 hours of recording head life and media with more than one million media passes. While the drives are expensive, DLT offers a reliable solution for migrating large volumes of data in a short backup window.

Mark Rogers is the tape business unit manager at Verbatim Corporation (Charlotte, NC).

                            THE SITUATION TODAY
                  WORLDWIDE TAPE DRIVE OEM REVENUES, 1999
Half Inch 21%
DLT       29%
8mm        8%
4mm       27%
SLR        4%
Travan    11%
$2.9 Billion
Source: IDC