Technologies for manufacturing hard disks are driven by the demand to increase magnetic storage capacity. However, the rate of increasing storage capacity is being slowed by the inability to produce ever closer flying heights between the sliders and disk surfaces. One of important requirements for flying height is to control the surface of substrates of hard disks to a super-smooth level to all...

The widely spread mobile consumer electronic devices, such as Android-based smartphones and tablets, have employed Ext4 file system as their main partition’s file systems. Although the performance of Ext4 file system has been researched and optimized for traditional hard disk drives under general workloads, extensive investigations are urgently required to improve its performance for consumer e...

Solid-state drives (SSDs) are quickly becoming an affordable alternative to mechanical hard disk drives. SSDs perform low latency reads and have access times that are magnitudes smaller than those of their mechanical counterparts. Many current file systems make clever optimizations that target mechanical hard disk drives; the faster performance of SSDs without use of mechanical parts makes obso...

To quote Shannon from his paper A Mathematical theory of communication: “The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point.” The basic setup of the communication problem consists of a source that generates digital information which is to reliably communicated to a destination through a channel, prefer...

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This paper uses the PES Pareto Method[1] and measurement techniques for isolating noise sources[2] to decompose the Position Error Signal (PES) of a Lynx II hard disk drive manufactured by Hewlett-Packard. This accomplishes three things: it demonstrates the utility of the PES Pareto Method in a practical example, it allows us to discover which noise sources are insignificant to PES, and it iden...

Wear particles in a hard disk drive may cause the head/disk interface to fail. We have experimentally investigated wear particle generation resulting from fretting wear between the dimple on the suspension and the gimbal spring. We have found that increasing the normal load as well as using a low friction coating reduces the formation of wear particles. INTRODUCTION Examination of failed hard d...

This paper proposes an object oriented framework to model and synthesize robust multi-rate controllers for many of the trackfollowing servo configurations encountered in the hard disk drive (HDD) industry, including traditional single-stage and new dual-stage servos. The proposed object oriented software will be used to synthesize and evaluate the tracking performance of different single-stage ...

This paper discusses optimal H∞ control synthesis via discrete Riccati equations for discrete linear periodically timevarying (LPTV) systems. Based on the results presented in [1], an explicit minimum entropy H∞ controller for general time-varying systems is obtained. The control synthesis technique is subsequently applied to LPTV systems and it is shown that the resulting controllers are also ...

The aim of performance evaluation is to find out some performance metrics for systems under consideration or for prototypes to workout novel systematic and methodological basis for some portions of performance evaluation, discover methods to use speculative methods in conceiving and assessing performance models. In this paper measurement based performance evaluation techniques have been applied...