嵌入式DVR文件系统的研究与设计

基于FAT32文件系统的数字视频录像系统(DVR)硬盘在长时间录像过程中产生大量文件碎片而导致硬盘存储效率显著下降.针对该问题,设计了一种能避免产生大量文件碎片并适应DVR硬盘录像需要的FAT32改进型文件系统.分析了基于FAT32文件系统的DVR硬盘文件存储和访问的特点,详细介绍了该文件系统的设计方案,并通过实例分析了系统的性能.     

浅析硬盘录像技术

本文概述了硬盘录像系统的基本结构和原理，并详细描述了其每一部分的实现原理，同时提出了作者对硬盘录像系统未来发展趋势的看法。     

DVR文件系统及硬盘发展趋势

在硬盘录像机中，录像功能和很多其它功能相关联，如放像功能，网络功能，备份功能等等，因此采用什么样的录像技术，直接关系到整个硬盘录像机的性能和硬盘故障率。录像技术分两个方面：一是采用什么样的文件系统。二是在已选定文件系统的条件下，系统如何发挥文件系统的优势，同时避免其弱点对整个系统造成影响。[编者按]     

2008年安防精品—深圳市景阳数码技术有限公司

SN-ADR410嵌入式数字硬盘录像系统；SN-ADR1016嵌入式数字硬盘录像系统；SN-MDR3000系列多功能车载数字硬盘信息管理系统；SN-MDR4000系列多功能车载数字硬盘信息管理系统；SN-MDR5000系列多功能车载数字硬盘信息管理系统[第一段]     

数字视频录像系统设计

介绍一种以高速DSP芯片TMS320VC5402为平台的数字视频录像系统。该系统采用脱离PC机独立工作的设计,应用MJPEG压缩技术和硬盘存储技术,比较好地实现了数字视频录像功能。     

网络DVR产品精选

NetServer系列网络视频监控主机,APP—DR6000网络硬盘录像机，EN—1604嵌入式网络硬盘录像机，DVS平台／嵌入式DVR平台，DVD直刻式投字硬盘录像系统。[编者按]     

大容量硬盘快速分区“三剑客”

现在，80～160GB的硬盘已成为消费主流。硬盘容量越大，分区和格式化花费的时间也就越长，例如，用FDISK对一个80GB的硬盘进行分区就需要近一个小时左右的时间，而且Windows 98系统中的FDISK命令也不支持64GB以上的大硬盘(Windows Me系统下自带的FDISK可支持大硬盘分区)。那么该如何提高系统分区的速度呢?本文就介绍几种快速分区格式化的方法。     

数码监控录像资料的非实时远程备份

如何规划录像硬盘的容量，以满足一定周期内视频点播的要求?如何选择一个合适的备份方案，以满足关键录像资料长期保存的要求?本文介绍的远程备份方案即有针对性地解决了这些问题。     

可连续存储23天视频——希捷推出SV35系列硬盘

3月16日,希捷公司宣布推出专门针对商业数字监控录像系统进行性能优化的硬盘——SV35系列。据悉,SV35系列硬盘有160GB、250GB和500GB三种规格,可以连续存储多达23天的高品质视频资料。希捷表示,视频读写注重流的可靠性,而数据读写则注重数据完整性。SV35硬盘支持ATA7命令集,可将读写模式调整为视频模式或数据模式,随时根据数据类型优化读写策略以获得最佳性能。另一方面,SV35系列硬盘和启动电流仅约2.0A,支持高效、低成本的供电设计,这使监控的数字录像系统应用多块硬盘变得更加简易。该硬盘还具有实时节电的特性,支持硬盘在非活动…     

国际新品

SISTORE MX Hybrid数字硬盘录像系统，RX304视频存储器，C-23编码器，Piexo防破坏紧急按钮，PC685高清彩色摄像机……     

Improvement of dynamic characteristics of a HDD spindle system supported by ball bearing at elevated temperature

This research investigates how the design variables of ball bearing affect the bearing stiffness and the natural frequencies of a hard disk drive (HDD) spindle system at elevated temperature. It shows that any design change that increases the contact angle of ball bearing reduces the variation in the bearing stiffness and the natural frequencies at elevated temperature. This research also proposes a robust HDD spindle motor in which a wave spring maintains a constant preload minimizing the effect of temperature variation. Experimental modal testing shows that the reduction of the natural frequencies at elevated temperature is much less in the proposed HDD spindle system than in the conventional spindle system. The proposed HDD spindle motor can improve the dynamic reliability of a HDD spindle system, which contributes to the high track density of a HDD.     

Whirling, tilting and axial motions of a HDD spindle system due to the manufacturing errors of FDBs

This paper investigates the whirling, tilting and axial motions of a hard disk drive (HDD) spindle system due to manufacturing errors of fluid dynamic bearings (FDBs). HDD spindle whirls around the sleeve with tilting angle due to the centrifugal force of unbalanced mass and the gyroscopic moment of rotating spindle in addition to axial motion. The whirling, tilting and axial motions may be increased by the manufacturing errors of FDBs such as imperfect cylindricity of sleeve bore, or imperfect perpendicularity between shaft and thrust plate. They increase the disk run-out to limit memory capacity and they may result in the instability of the HDD spindle system. This paper proposes the modified Reynolds equations for the coupled journal and thrust FDBs to include the variable film thickness due to the cylindricity of sleeve bore and the perpendicularity between shaft and thrust plate. Finite element method is used to solve the modified Reynolds equation to calculate the pressure distribution. Reaction forces and friction torque are obtained by integrating the pressure and shear stress, respectively. The whirling, tilting and axial motions of the HDD spindle system are determined by solving the equations of a motion of a HDD spindle system in six degrees of freedom with the Runge-Kutta method. It shows that the imperfect cylindricity and perpendicularity increase the whirl radius, axial runout and tilting angle of the HDD spindle system. However, the degradation of dynamic performance due to the imperfect perpendicularity between shaft and thrust plate can be improved by allowing the other manufacturing error of the cylindricity of sleeve bore in such a way to compensate the bad effect of the imperfect perpendicularity.     

Dynamic analysis of a HDD spindle system with FDBs due to the bearing width and asymmetric grooves of journal bearing

This paper investigates the dynamic behavior of a HDD spindle system with fluid dynamic bearings (FDBs) by solving the Reynolds equation and the equations of a motion of a HDD spindle system in five degrees of freedom. FEM is used to solve the Reynolds equation in order to calculate the pressure distribution in fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors of a HDD spindle system, such as the whirling and the tilting motion, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This paper also proposes two design methods to improve the dynamic characteristics of a HDD spindle system without increasing friction torque, i.e., optimization of the width of the lower and the upper journal bearings and the journal bearings with asymmetric grooves.     

A hybrid filesystem for hard disk drives in tandem with flash memory

The traditional hard disk drive (HDD) is often a bottleneck in the overall performance of modern computer systems. With the development of solid state drives (SSD) based on flash memory, new possibilities are available to improve secondary storage performance. In this work, we propose a new hybrid SSD–HDD storage system and a selection of algorithms designed to assign pages across an HDD and an SSD to optimise I/O performance. The hybrid system combines the advantages of the SSD’s fast random seek speed with the sequential access speed and large storage capacity of the HDD to produce significantly improved performance in a variety of situations. We further improve performance by allowing concurrent access across the two types of storage devices. We show the drive assignment problem is NP-complete and accordingly propose effective heuristic solutions. Extensive experiments using both synthetic and real data sets show our system with a small SSD can outperform a striped dual HDD and remain competitive with a dual SSD.     

Analysis of dynamic characteristics of a HDD spindle system supported by ball bearing due to temperature variation

 This paper presents a method to investigate the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. Finite element model is developed for the rotating and stationary parts of a HDD spindle system separately to determine their thermal deformations by using ANSYS, a finite element program. Then, the relative position of the rotating part with respect to the stationary part is determined by solving the equilibrium equation of the contact force between upper and lower ball bearings. The validity of the proposed method is verified by comparing the theoretical natural frequencies of a HDD spindle system with the experimental ones before and after temperature variation. The proposed method makes it possible to predict the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. It shows that the elevated temperature results in the increase of contact angle and the decrease of bearing deformation, contact force and bearing stiffness, which result in the decrease of the natural frequencies of a HDD spindle system. Received: 20 June 2002 / Accepted: 28 August 2002     

Analysis of contact phenomena between a head stack assembly and disk during operational shock

A hard disk drive (HDD) is very sensitive to shock. Increasing portability demands have led to increased HDD exposure to unexpected shocks. Therefore, the dynamic characteristics of an HDD were utilized to investigate the relative behavior of the disk and head stack assembly (HSA) during operational shock. A finite element model of HDD was constructed to simulate operational shock. This model included the spindle system, base, HSA, and disk. The relative behavior of the disk and HSA was analyzed using different bases with different stiffness. A drop test was performed to verify the simulation results. A modified base design was then proposed to protect against contact between the disk and HSA in HDD.     

Drive level acoustic defectoscopy for head disc interface (HDI) integration and manufacturing

A short product development cycle for modern hard disc drive (HDD) depends entirely on early defect characterization. However, deviations from desired HDI mechanical performance are not always manifested in electromagnetic read back or servo control signals. The best non-destructive tool to monitor HDI dynamics at the HDD level is a passive acoustic technique that tracks equilibrium of the head gimbal assembly and air bearing (AB) modes. This technique is capable of active head protrusion detection as well as detection of embedded particles. The drawback of the passive acoustic monitoring technique at drive level is that a noisy HDD environment makes the detectability of a useful signal challenging. The proposed HDD level in situ passive HDI acoustic monitoring technique consists of external AE sensors driven by adequate electronics. These are enhanced by advanced signal processing routines that include adaptive discrete wavelet transforms. The system is tuned to monitor acoustic HDI signatures during drive spin-up/spin-down cycles as well as during passive and active height across the data zones. In addition, integrated acoustic energy metrics can be used in AB design evaluation stages. In this work examples of HDD level passive acoustic monitoring applications for HDI development, and manufacturing defect tracking, are presented and supported by failure analysis results.     

Assessment of the risk imposed by the presence of corroded shallow voids on the initialization and long-term reliability of hard disk drives

Microsystem Technologies - This paper investigates how corrosion growth that originates from shallow film voids on thin film sputtered magnetic media can impact the final HDD system performance....     

NAND flash memory-based hybrid file system for high I/O performance

As the performance potentials of SSD (Solid State Device) have been recognized, adopting SSD to IT products as HDD replacements is rapidly increasing. Since SSD is organized into multiple flash memory packages, it deploys peculiar device characteristics that do not occur in HDD, such as block-unit erasure overhead. Also, its high cost per capacity is the main obstacle to building a large-scale storage subsystem with only SSDs. An alternative is to build a hybrid storage subsystem where a small portion of SSDs are integrated with HDDs so as to utilize SSD’s performance advantages in a cost-effective way. This study introduces a new form of file system, called N-hybrid (New-Form of hybrid file system), that enables us to support the hybrid device structure combined with both HDD and SSD. Our primary objectives in developing N-hybrid are to provide better I/O bandwidth by exploiting the characteristics of HDD and SSD and to provide a flexible data layout maximizing the usage of tight SSD storage resources. Several experiments were conducted to verify the effectiveness and suitability of N-hybrid.     

Effect of disk support system dynamics on the stability of head–disk interface during an operational shock in a mobile hard disk drive

There has been a substantial increase in the demand of hard disk drives (HDD) for mobile electronic devices like laptop, camcorders, etc. Mobile HDDs are often subjected to harsh working environments and hence require higher shock resistance for better reliability performance. In this paper, we develop a model for the mobile disk drive to numerically investigate the dynamics of the head–disk interface (HDI) during an operational shock. The results show that the disk and its support system design have a strong influence on the shock resistance. This study can help improve the HDD components and air bearing design for a better shock performance.