On-Disk Data Processing: Issues and Future Directions

In this paper, we present a survey of "on-disk" data processing (ODDP). ODDP, which is a form of near-data processing, refers to the computing arrangement where the secondary storage drives have the data processing capability. Proposed ODDP schemes vary widely in terms of the data processing capability, target applications, architecture and the kind of storage drive employed. Some ODDP schemes provide only a specific but heavily used operation like sort whereas some provide a full range of operations. Recently, with the advent of Solid State Drives, powerful and extensive ODDP solutions have been proposed. In this paper, we present a thorough review of architectures developed for different on-disk processing approaches along with current and future challenges and also identify the future directions which ODDP can take.Comment: 24 pages, 17 Figures, 3 Table

REAL-TIME SIGNAL PROCESSING FOR FLYING HEIGHT MEASUREMENT AND CONTROL IN HARD DRIVES SUBJECT TO SHOCK AND VIBRATION

Merged with duplicate record 10026.1/829 on 10.04.2017 by CS (TIS)Three readback signal detection methods are investigated for real-time flying height or head disk spacing variation measurement under vibration conditions. This is carried out by theoretical analysis, numerical simulation, and experimental study. The first method (amplitude detection) provides a simple way to study the head disk spacing change. The second method ( PW50 parameter estimation) can be used effectively for real-time spacing variation measurement in normally operated hard disk drives, primarily in low frequency spacing variation conditions. The third method (thermal signal detection), on the other hand, is more effective and suitable for high frequency spacing variation measurement. By combining the PW50 estimation and thermal signal detection methods, a noval spacing variation detection method for the whole frequency range is constructed. This combined signal detection method not only has been used to study the head disk spacing variation itself, but also has the potential of being used for real time flying height control. Analytical models are developed for head disk assembly and head position servo control mechanisms to analyse the operation failure of hard disk drives under vibration conditions. Theoretical analysis and numerical simulation show their good agreement with experimental results. A novel active flying height control method is proposed to suppress the flying height or head-disk spacing variation in hard disk drives under vibration conditions. Simulation results show that this active flying height control can effectively suppress the head-disk spacing variation, therefore the performance and reliability of HDDs can be well improved when working in vibration conditions: The method has a good potential to be applied to future ruggedized hard disk drives

Forensic Research on Solid State Drives using Trim Analysis

There has been a tremendous change in the way we store data for the past decade. Hard Disk Drives, which were one of the major sources of storing data, are being replaced with Solid State Drives considering the higher efficiency and portability. Digital forensics has been very successful in recovering data from Hard Disk Drives in the past couple of years and has been very well established with Hard Disk Drives. The evolution of Solid State Drives over Hard Drive Drives is posing a lot of challenges to digital forensics as there are many crucial factors to be considering the architecture and the way data is stored in Solid State Drives. This paper gives a very detailed picture of the evolution of Solid State Drives over Hard Disk Drives. We understand the differences in their architecture and the ways to extract data from them. We further discuss in detail the various challenges Solid State Drives pose to the field of digital forensics, and we try to answer contradictory beliefs those are 1) Would data be permanently deleted in a Solid State Drives destroying the forensic evidence required to solve a case? 2) Can data be restored in a Solid State Drives by using proper techniques and still can be used as evidence in digital forensics? In this paper, we talk about the introduction of concepts such as the TRIM Command and Garbage collection, their importance, and we set up an experimental scenario where we implement the TRIM command and try extracting data from different types of Solid State Drives. We compare and evaluate the results obtained through the experiment and try to analyze the uses of the TRIM command and its performance over various Solid State Drives. The paper also discusses future work to make the role of Solid State Drives more efficient in digital forensics

Processing Internal Hard Drives - cover page

As archives receive born digital materials more and more frequently, the challenge of dealing with a variety of hardware and formats is becoming omnipresent. This paper outlines a case study that provides a practical, step-by-step guide to archiving files on legacy hard drives dating from the early 1990s to the mid-2000s. The project used a digital forensics approach to provide access to the contents of the hard drives without compromising the integrity of the files. Relying largely on open source software, the project imaged each hard drive in its entirety, then identified folders and individual files of potential high use for upload to the University of Texas Digital Repository. The project also experimented with data visualizations in order to provide researchers who would not have access to the full disk images—a sense of the contents and context of the full drives. The greatest challenge philosophically was answering the question of whether scholars should be able to view deleted materials on the drives that donors may not have realized were accessible

A Rule Based Forecast of Hard Disk Drive Costs

While the cost of storage devices such as hard disk drives continues to fall, the overall proportion of computer network costs dedicated to storage continues to rise. Within a few years, storage will account for 50 percent of total network hardware and software costs. Since computer networks typically have long lives, the design process often involves projecting costs many years into the future. This paper examines a rule based on a technology trend that can be used to estimate the cost per megabyte of hard disk drives. The rule is similar to the well-known Moore’s law that has reliably summarized integrated circuit advances over the past several decades. A statistical analysis of historic data suggests the rule for hard disk drives captures much of the readily available information

Hard Disk Storage: Firmware Manipulation and Forensic Impact and Current Best Practice

The most common form of storage media utilized in both commercial and domestic systems is the hard disk drive, consequently these devices feature heavily in digital investigations. Hard disk drives are a collection of complex components. These components include hardware and firmware elements that are essential for the effective operation of the drive. There are now a number of devices available, intended for data recovery, which can be used to manipulate the firmware components contained within the drive. It has been previously shown that it is possible to alter firmware for malicious purposes, either to conceal information or to prevent the drive’s correct operation. We review the general construction of a hard disk drive. In particular we examine the error handling process present within hard disk drives for dealing with failed or failing sectors and detail how this can be manipulated. The potential forensic impact on an investigation of manipulating firmware is then explored. We propose best practice considerations when analyzing a hard drive where firmware manipulation is suspected and detail a possible method to detect this form of modification. Keywords: Hard Disk, Steganography, Data Recovery, Firmware

A Study of Disk Performance Optimization.

Response time is one of the most important performance measures associated with a typical multi-user system. Response time, in turn, is bounded by the performance of the input/output (I/O) subsystem. Other than the end user and some external peripherals, the slowest component of the I/O subsystem is the disk drive. One standard strategy for improving I/O subsystem performance uses high-performance hardware like Small Computer Systems Interface (SCSI) drives to improve overall response time. SCSI hardware, unfortunately, is often too expensive to use in low-end multi-user systems. The low-end multi-user systems commonly use inexpensive Integrated Drive Electronics (IDE) disk drives to keep overall costs low. On such IDE based multi-user systems, reducing the Central Processing Unit (CPU) overhead associated with disk I/O is critical to system responsiveness. This thesis explores the impact of PCI bus mastering Direct Memory Access (DMA) on the performance of systems with IDE drives. DMA is a data transfer protocol that allows data to be sent directly from an attached device to a computer system’s main memory, thereby reducing CPU overhead. PCI bus mastering allows modern IDE disk controllers to manipulate main memory without utilizing motherboard-resident DMA controllers. Using a series of experiments, this thesis examines the impact of PCI bus mastering DMA on IDE performance for synchronous I/O, relative to Programmed Input/Output (PIO) and SCSI performance. Experiment results show that PCI bus mastering DMA, when used properly, improves the responsiveness and throughput of IDE drives by as much as a factor of seven. The magnitude of this improvement shows the importance of operating system support for DMA in low-end multi-user systems. Additionally, experimental results demonstrate that performance gains associated with SCSI are dependent on system usage and operating system support for advanced SCSI capabilities. Therefore, under many circumstances, high-performance SCSI drives are not cost effective when compared with IDE bus mastering DMA capable drives