Characterization and Simulation of MIMO Transport Systems in Tape

The potential for significant capacity and performance improvements in tape storage systems appears to be substantial [1],[2]. Advances in several areas, however, are necessary to foster increases in linear and track densities and consequently achieve higher cartridge capacities and improved performance [3],[4]. Reliable and precise tape transport and track-following servomechanisms are of fundamental importance to guarantee best read-channel performance on all parallel data channels during tape operation. In particular, tight control of tension and potentially of tape-dimensional stability (TDS) variations will be necessary for moving to thinner tape material, which in turn will enable an increase in volumetric density. Figure 1 shows the block diagram of conventional tape transport and track-following servomechanisms in a tape drive [5]. A digital dual servo channel provides estimates of the tape velocity, tape longitudinal position, and head lateral position, which are derived from signals read from dedicated servo bands [6]. Hall sensors provide tape velocity information from the individual reels, which typically is used in the absence of a valid velocity estimate from the servo channel. One of the main impairments affecting the performance of tape drives is the variation of tape tension [7],[8], which may be induced by, e.g., reel eccentricities.