Wednesday, April 25, 2007
Scientific advancements continue to drive tape's market leadership
While electronic data generation continues to grow at an 80% annual rate globally, according to IDC, the tape industry is keeping pace with the introduction of larger capacity, faster data transfers, and more scalable products that provide even better returns on investment that provides the protection of your business' data. Unlike their magnetic disk cousins (where the understood physical limits of the medium are continually being challenged and redefined) tape manufacturers have proven that there is at least another 16-fold capacity increase possible by using technologies and materials that are already being tested in their labs.
It is well established that tape is the most cost-effective media for storing large amounts of data. And even as disk capacities have dramatically increased over the past 10 years, the tape industry has continually maintained a capacity advantage over disk; a single tape cartridge can be used to backup the contents of a single hard drive. This has always been the case, and it continues to be the driving imperative behind tape drive and media development.
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The science behind the improvements in tape technology is very impressive, and also very technically sophisticated. Over 40 researchers representing the major tape drive manufacturers, tape media suppliers and many of the leading research universities, collaborated (as part of the Information Storage Industry Consortium--INSIC) to analyze enterprise tape market requirements. The result was the development in 2001 of a 10-year projection for the future of magnetic tape storage. INSIC's work indicates that to remain an economically viable storage solution when compared to disk, tape capacity must grow at a rate comparable to future disk capacity growth on a cost-per-gigabyte basis.
Although disk densities are continuing to rise, the rate of growth is expected to slow as disk recording nears a superparamagnetic limitation. Due to a much lower areal recording density and much greater recording area, tape technology has the potential to grow at a faster rate and as a result improve its cost per gigabyte trends compared to disk. Therefore, when combined with disk in the enterprise storage environment, the tape industry roadmap currently maintains that tape capacity on a single cartridge must achieve 10 terabytes (TB) uncompressed per cartridge by 2011, and must reach 1TB uncompressed on a single cartridge by 2006 on its way to reaching the 10-year goal.
Areal Density
One way to increase storage capacity is to increase the areal density of the medium. Areal density is the number of bits that can be reliably stored on, and retrieved from, a fixed surface size, such as a square inch on the tape or disk. In the mid-1990s, physicists announced the theoretical areal density limit of magnetic disk at 36GB/[in.sup.2], and expected to hit the actual limits somewhere before this theoretical limit. Today, that limit has been surpassed and driven to top-of-the-line enterprise disk drive models of 75GB/[in.sup.2].
Today's mid-range quarter-inch linear tape drives can store data at about .25 to .35 GB/[in.sup.2] on tape media, which is 200 times less than that of a mid-range magnetic hard disk of 65 GB/[in.sup.2] on a 3.5-inch platter. If you consider a half-inch linear tape cartridge, it is 1000 times that of a 3.5-inch platter. The capacity advantage of tape is its large volumetric density of tape in a given cartridge. While this may seem like tape is technically behind disk, tape drive design has kept pace with overall capacity increases, while tape reliability and data retention longevity have increased.
"Disk and tape scientific and engineering advances have been applied to each technology's products," states John Goode, Quantum's Tape Storage Product marketing manager. "These include the development of new, smaller magnetic particles, improved methods of placing these particles on the medium, and smaller, more responsive read/write heads with more parallel data channels."
Greatly improved methods for detecting and recovering from errors have also helped to push the limits of tape and disk capacity. Simple parity schemes have been replaced by complex algorithms, including Partial Response Maximum Likelihood (PRML), to make intelligent decisions on what the recorded content really should be.
As improvements in magnetic media design continue, the developers of tape drives and media have more technology to work with to improve their products. But even if and when magnetic media (particularly disk engineers) do hit the areal density wall, tape engineers will still have many generations of capacity improvements to come, due to the 800:1 ratio in areal density that currently exists between disk and tape design. Another way to look at this would be to say that current tape cartridges contain 800 times the recording surface of a disk drive.
It is well established that tape is the most cost-effective media for storing large amounts of data. And even as disk capacities have dramatically increased over the past 10 years, the tape industry has continually maintained a capacity advantage over disk; a single tape cartridge can be used to backup the contents of a single hard drive. This has always been the case, and it continues to be the driving imperative behind tape drive and media development.
[GRAPHIC OMITTED]
Advertisement
The science behind the improvements in tape technology is very impressive, and also very technically sophisticated. Over 40 researchers representing the major tape drive manufacturers, tape media suppliers and many of the leading research universities, collaborated (as part of the Information Storage Industry Consortium--INSIC) to analyze enterprise tape market requirements. The result was the development in 2001 of a 10-year projection for the future of magnetic tape storage. INSIC's work indicates that to remain an economically viable storage solution when compared to disk, tape capacity must grow at a rate comparable to future disk capacity growth on a cost-per-gigabyte basis.
Although disk densities are continuing to rise, the rate of growth is expected to slow as disk recording nears a superparamagnetic limitation. Due to a much lower areal recording density and much greater recording area, tape technology has the potential to grow at a faster rate and as a result improve its cost per gigabyte trends compared to disk. Therefore, when combined with disk in the enterprise storage environment, the tape industry roadmap currently maintains that tape capacity on a single cartridge must achieve 10 terabytes (TB) uncompressed per cartridge by 2011, and must reach 1TB uncompressed on a single cartridge by 2006 on its way to reaching the 10-year goal.
Areal Density
One way to increase storage capacity is to increase the areal density of the medium. Areal density is the number of bits that can be reliably stored on, and retrieved from, a fixed surface size, such as a square inch on the tape or disk. In the mid-1990s, physicists announced the theoretical areal density limit of magnetic disk at 36GB/[in.sup.2], and expected to hit the actual limits somewhere before this theoretical limit. Today, that limit has been surpassed and driven to top-of-the-line enterprise disk drive models of 75GB/[in.sup.2].
Today's mid-range quarter-inch linear tape drives can store data at about .25 to .35 GB/[in.sup.2] on tape media, which is 200 times less than that of a mid-range magnetic hard disk of 65 GB/[in.sup.2] on a 3.5-inch platter. If you consider a half-inch linear tape cartridge, it is 1000 times that of a 3.5-inch platter. The capacity advantage of tape is its large volumetric density of tape in a given cartridge. While this may seem like tape is technically behind disk, tape drive design has kept pace with overall capacity increases, while tape reliability and data retention longevity have increased.
"Disk and tape scientific and engineering advances have been applied to each technology's products," states John Goode, Quantum's Tape Storage Product marketing manager. "These include the development of new, smaller magnetic particles, improved methods of placing these particles on the medium, and smaller, more responsive read/write heads with more parallel data channels."
Greatly improved methods for detecting and recovering from errors have also helped to push the limits of tape and disk capacity. Simple parity schemes have been replaced by complex algorithms, including Partial Response Maximum Likelihood (PRML), to make intelligent decisions on what the recorded content really should be.
As improvements in magnetic media design continue, the developers of tape drives and media have more technology to work with to improve their products. But even if and when magnetic media (particularly disk engineers) do hit the areal density wall, tape engineers will still have many generations of capacity improvements to come, due to the 800:1 ratio in areal density that currently exists between disk and tape design. Another way to look at this would be to say that current tape cartridges contain 800 times the recording surface of a disk drive.
# posted by Medical Information : 4:28 AM
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