Tape systems scaling

 

The linear tape recording performance of a prototype barium ferrite tape was investigated using a 90-nm-wide giant-magnetoresistive reader and a prototype enhanced field write head that enables the use of reduced volume BaFe particles with increased coercivity. A linear density of 600 kbpi was demonstrated based on measured recording data and a simulated read channel that used a data dependent noise predictive maximum likelihood detection scheme. Using a new iterative decoding architecture we can achieve a user bit error rate <10−20 at this operating point.

To facilitate aggressive scaling of the track density, we made several advances in the area of track follow performance. First we developed a low noise experimental tape transport. Second, we implemented a new servo channel that together with an experimental timing based servo pattern enables the generation of position estimates with nanoscale resolution at a high update rate.

Third, we developed an FPGA based prototyping platform in which we have implemented the servo channel and a tape speed optimized H-infinity based track follow controller, enabling real time closed loop track follow experiments with minimal delay. Combing these technologies, we achieved a position error signal (PES) with a 1-sigma standard deviation of 10.3 nm over the full speed range of an IBM enterprise class TS1140 tape drive. This magnitude of PES in combination with a 90-nm-wide reader leads to an estimated track width of 177 nm and a track density of 143 ktpi. Finally, combining this track density with the linear density of 600 kbpi achieved within the error rate target with the 90 nm reader enables an areal recording density of 85.9 Gb/in2. This result clearly demonstrates the scalability and extendability of tape technology using low-cost particulate media [2014-1].