Imation Previews Super-Dense Adjacent Track Tape Tech
February 25, 2008 Timothy Prickett Morgan
Researchers at Imation, the magnetic tape manufacturer that was spun out of 3M in 1996 and which is one of the dominant makers of removable data storage media, recently announced a new breakthrough in its tape technology that will allow it to double the capacity on existing LTO-4 tape cartridges.
Materials scientist Denis Langlois from Imation recently demonstrated a new multichannel, adjacent track data writing and reading technique that the company has created for LTO-4 tapes. The new technique was shown at the Information Storage Industry Consortium trade show in San Jose, one of the epicenters of storage technology and one of the hot spots where IBM and 3M worked together to create the first tape drives for computers back in 1952.
That was the Model 726 tape drive, which used a 12-inch movie reels loaded with magnetic tape and which could store a whopping 1.4 megabytes of data on a reel. Since that time, the areal density of tape media has increased by a factor of 100,000. Imation says that from the 1950s and the 1990s, the density increases for tape drives came primarily for increasing the data density of the tape media, but since then, the manner in which tracks are written down–and the skinniness of the tracks–has been a more important factor. Data tracks have long since not been laid down in parallel lines lengthwise on the tape, and employ a variety of sophisticated techniques to interleave data so reads and writes can be done in a timely fashion even as tapes get denser and tape drives hit physical limits on how fast they can roll a bit of tape over a tape head.
According to Imation, the adjacent track recording technique uses regular magnetic tape, but employs an amplitude-based servo pattern to lay down tracks that are adjacent to the normal LTO tracks and then uses a new thin-film head to write data to the tape and a new multi-layer magneto-resistive array for reading the data back off the tape.
“The application of a track-following servo has enabled track density to make a more dramatic contribution,” explains Subodh Kulkarni, vice president of research, development, and manufacturing for Imation’s global commercial business. “To maintain backward compatibility, designers have kept tape formats similar from generation to generation by using the same servo format and channel spans on the recording and playback heads. This design philosophy results in the need to simultaneously write and read sets of tracks that are spaced apart by significant intervals, which makes the dimensional stability of the substrate materials very critical as tracks become narrower. Without a breakthrough approach to how tracks are written on the tape, conventional, low-cost, substrates are rapidly reaching their limits. Our new adjacent-track write and read technology is an important breakthrough that has demonstrated a major advance in capacity and track-following capability.”
The ability to double the capacity of an LTO-4 cartridge to 1.6 TB, and therefore take the pressure off development of the LTO-5 drives and matching tape technology, is something that Imation is pitching to the tape industry. Without the adjacent track recording technique, LTO-5 is on track to deliver tape drives with 1.6 TB capacity, double that of LTO-4 drives, with a 50 percent boost in data transfer rate to 180 MB/sec. The LTO-5 spec is expected to be finished in the first or second quarter of 2009, and LTO-6 will push out drives that can handle 270 MB/sec of bandwidth on tapes that max out at 3.2 TB. (Those data rates are not including data compression, as are the capacities.) It would be interesting to see if the existing LTO-5 and LTO-6 technologies can be augmented with the adjacent track technique, allows capacities and data transfer rates to climb even faster than the LTO roadmaps have set.