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Where will tape wind up?

whatever bells-and-whistles each technology proponent is pushing, capacity and speed are the two main criteria CIOs look at when comparing tape storage alternatives available today

Linear format tape technology has been time-tested and market proven to have a long lifespan that is key for data protectioN. The mechanical simplicity of linear technology means there are few moving parts, providing durability and lower maintenance

A study released by UC Berkeley's School of Information Management and System last year estimated that between one to two exabytes (1018 bytes) of unique data is produced each year. Put another way, it is roughly equivalent to 250 MB of data for every man, woman and child on earth!

The next question is naturally, how is all this data being stored? About 80 percent of all this data is stored digitally, with the remainder in print form or on film. With new information being created every single day,

organizations have to find cost-effective ways to store and backup their data, with the ability to retrieve quickly and effectively.

Over 40 and going strong

Tape storage was invented by IBM scientists in 1952, and has proved to be one of the most enduring technologies the industry has seen. Today, tape remains the preferred media for backup and recovery because of its lower cost per megabyte, reliability and durability.

The evolution of the tape storage technology has received a boost in recent years from a few quarters. For a start, while the dotcom bubble has burst, the momentum created by the era is propelling the world into the information age like never before. This in turn is leading to a trend of building Storage Area Networks (SANs) to provide centralized management of diverse storage resources through the network.

Finally, the introduction of new tape formats like Linear Tape Open (LTO) addressing the limitations of existing technology has reassured CIOs that tape remains a reliable, affordable and viable technology for their company's back-up needs.

Back up a minute

An industry rule of thumb suggests that there is about 10 times as much storage on tape as on hard drives. According a recent International Data Corporation study on the tape drive market, 4.5 million tape drives will be shipped in 2001 alone.

Linear format tape technology has been time-tested and market proven to have a long lifespan that is key for data protection. The mechanical simplicity of linear technology means there are few moving parts, providing proven durability and lower maintenance costs.

But whatever bells-and-whistles each technology proponent is pushing, capacity and speed are the two main criteria CIOs look at in comparing the alternatives available today.

Capacity: With data growing as fast as it is, companies are putting pressure on storage vendors for more capacity in the same form factor. For example, the DLT format that dominates the market today offers only 40 GB native capacity (80 GB compressed). This means more cartridges are required and more precious IT man-hours spent manning the drives, removing and inserting new cartridges .

Speed: Depending on the industry and company, backup can be done daily or weekly. It is usually done in the middle of the night as the business applications being backed-up usually had to be brought down for this purpose. The faster the data transfer rate of a tape solution, the shorter will be the backup window and downtime-a major plus in an age of 24-hour-a-day customer service.

A comparison of LTO and Super DLT

One of the main drivers pushing tape vendors is the demand for very large and shareable data repositories brought on by e-business and SAN.

With this comes a corresponding need to be able to retrieve data backed-up on tape as quickly as possible. In a situation where a company has suffered the catastrophic loss of its data on primary server drives, the speed at which its business can get up and running again is absolutely dependent on the speed at which its data can be retrieved.

IBM-Hewlett Packard-Seagate's Linear-Tape Open (LTO) and Quantum's Super DLT represent the two most advanced tape technology formats available today.

Capacity: Today, Quantum's Super DLT tape cartridge boasts the higher capacity of the two with 110 GB native capacity compared to LTO's 100 GB. However, the only product available today is the Quantum Super DLT 220 that offers a single tape drive with a single cartridge. The LTO family today offers a range of products from a one drive/one cartridge product to an ultra-scaleable tape library which can contain up to 72 drives and 496.2 TB compressed capacity.

Quantum has promised that future generations of Super DLT will deliver up to one terabyte of capacity and a 100 MB/second data transfer rate. Today, the LTO consortium has already unveiled a clearly

defined four-generation roadmap that will see its capacity doubling with each generation to 200 GB (by 2002), 400 GB and 800 GB in the next few years.

Speed: As the saying goes, this is where the rubber hits the road.

More important than the capacity is the speed to backup and restore the data. Allowed time frames for backup are becoming shorter, and the data rate is becoming one of the leading factors for choosing a tape technology.

Here LTO has an edge over Super DLT with a 15 MB/second uncompressed data transfer rate over the latter's 11MB/second.

In tests run with two typical back-up scenarios where 200 GB and 800 GB of data have to be written in 2 hours, LTO demonstrated its superiority immediately.

Because of the higher data rate of IBM LTO Ultrium, in each case it was found that fewer drives and therefore lower costs were needed to backup the specified amount of data in a defined time.

An independent data recovery exercise run by the IT Manager for CMP Asia, a global publishing house, they found that with IBM's LTO solution, they were able to shorten the backup window by 25 percent, compared to their previous experience with DLT.

The Eddy Group, a US utilities

company, was similarly impressed by LTO. "We wanted more speed than we had, but this is astounding. Now, a full backup takes just five minutes down from over two hours."

Conclusion

Competition is a healthy state of affairs for the industry. It keeps vendors on their toes to keep pushing the technology envelope.

Which is why the goal of the LTO Consortium to offer a truly open standard that supports data interchange among multiple vendors' products is a laudable one. A choice of vendors and a clearly defined roadmap endorsed by the top

storage companies can only mean good news for customers.

Where will tape wind up? Everywhere.

Sandeep Dutta is the Country Business Manager, Storage, IBM India and can be reached at sandutta@in.ibm.com. (The opinion expressed in thisarticle is the author's own)

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