Diskうねり追従時におけるSlider Pitchingの位相遅れ

抄録

In recent years, hard disk drives (HDDs) have been mainly used in cloud data centers, and their data structure uses the log-structured merge-tree (LSM-Tree) which undergoes many rewrites, resulting in a workload requirement of 550TB write/year. A 5-year product warranty is currently required, and there seems to be a desire to extend it to 6-7 years in the future. Therefore, reliability is one of the most important characteristics of HDDs. On the other hand, because current head media spacing (HMS) is less than 1nm, intermittent head to disk contact frequently occurs, increasing the risk of head wear, head smear, media scratches, and so on. As countermeasures, many studies have been conducted, including research on soft contact detection methods, bouncing, research on head protrusion, bouncing and surfing during touchdown, and so on. However, there seems to be little research on the mechanisms of intermittent contact and repeatable HMS fluctuations. In this paper, we calculated the static change amount of slider pitching to keep the slider pitch angle constant with respect to the disk when following the disk waviness. We also calculated the dynamic behavior of slider pitching when the change amount is input using a one-degree-freedom model. As a result, we found that one of the factors in HMS fluctuation was the phase delay of slider pitching, and its parameters were extracted.