• Title/Summary/Keyword: Disk Failure

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Recovery Management of Split-Brain Group in Highly Available Cluster file System $\textrm{SANique}^{TM}$ (고가용성 클러스터 파일 시스템 $\textrm{SANique}^{TM}$의 분할그룹 탐지 및 회복 기법)

  • 이규웅
    • Journal of Korea Multimedia Society
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    • v.7 no.4
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    • pp.505-517
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    • 2004
  • This paper overviews the design details of the cluster file system $\textrm{SANique}^{TM}$ on the SAN environment. $\textrm{SANique}^{TM}$ has the capability of transferring user data from shared SAN disk to client application without control of centralized file server. We, especially, focus on the characteristics and functions of recovery manager CRM of $\textrm{SANique}^{TM}$. The process component for failure detection and its overall procedure are described. We define the split-brain problem that cannot be easily detected in cluster file systems and also propose the recovery management method based on SAN disk in order to detect and solve the split-brain situation.

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Nano-Wear and Friction of Magnetic Recording Hard Disk by Contact Start/Stop Test

  • Kim, Woo Seok;Hwang, Pyung;Kim, Jang-Kyo
    • KSTLE International Journal
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    • v.1 no.1
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    • pp.12-20
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    • 2000
  • Nano-wear and friction of carbon overcoated laser-textured and mechanically-textured computer hard disk were characterised after contact start/stop (CSS) wear test. Various analytical and mechanical testing techniques were employed to study the changes in topography, roughness, chemical elements, mechanical properties and friction characteristics of the coating arising from the contact start/stop wear test These techniques include: the atomic force microscopy (AFM), the continuous nano-indentation test, the nano-scratch test, the time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and the auger electron spectroscopy (AES). It was shown that the surface roughness of the laser-textured (LT) bump and mechanically textured (MT) Bone was reduced approximately am and 7nm, respectively, after the CSS wear test. The elastic modulus and hardness values increased after the CSS test, indicating straining hardening of the top coating layer, A critical load was also identified fer adhesion failure between the magnetic layer and the Ni-P layer, The TOF-SIMS analysis also revealed some reduction in the intensity of C and $C_2$$F_59$, confirming the wear of lubricant elements on the coating surface.

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Brazilian Test of Concrete Specimens Subjected to Different Loading Geometries: Review and New Insights

  • Garcia, Victor J.;Marquez, Carmen O.;Zuniga-Suarez, Alonso R.;Zuniga-Torres, Berenice C.;Villalta-Granda, Luis J.
    • International Journal of Concrete Structures and Materials
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    • v.11 no.2
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    • pp.343-363
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    • 2017
  • The objective of this work was finding out the most advisable testing conditions for an effective and robust characterization of the tensile strength (TS) of concrete disks. The independent variables were the loading geometry, the angle subtended by the contact area, disk diameter and thickness, maximum aggregate size, and the sample compression strength (CS). The effect of the independent variables was studied in a three groups of experiments using a factorial design with two levels and four factors. The likeliest location where failure beginning was calculated using the equations that account for the stress-strain field developed within the disk. The theoretical outcome shows that for failure beginning at the geometric center of the sample, it is necessary for the contact angle in the loading setup to be larger than or equal to a threshold value. Nevertheless, the measured indirect tensile strength must be adjusted to get a close estimate of the uniaxial TS of the material. The correction depends on the loading geometry, and we got their mathematical expression and cross-validated them with the reported in the literature. The experimental results show that a loading geometry with a curved contact area, uniform load distribution over the contact area, loads projected parallel to one another within the disk, and a contact angle bigger of $12^{\circ}$ is the most advisable and robust setup for implementation of BT on concrete disks. This work provides a description of the BT carries on concrete disks and put forward a characterization technique to study costly samples of cement based material that have been enabled to display new and improved properties with nanomaterials.

Dynamics of a Pico Slider during the Ramp Loading Process (Ramp Loading 피코 슬라이더의 거동 해석)

  • Rhim Yoon-Chul;Kim Bum-Joon;Cho Kwang-Pyo
    • Tribology and Lubricants
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    • v.20 no.6
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    • pp.322-329
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    • 2004
  • Recently, a load/unload(L/UL) system is adopted to the hard disk drive(HDD) due to its advantages such as lower power consumption, larger data zone, simpler fabrication of disk due to no bumped parking zone, and rarer contact between slider and media. An analysis of the transient motion for the slider is very important to design an air bearing surface(ABS) of the slider to secure the stable performance of the system. During the L/UL process, however, there are several issues occurred such as contact or collision between slider and media. Sometimes this will cause the system failure. In this study, the dynamics of a pico slider during the loading process are investigated through numerical simulation using FEM analysis and experiment. Ramp profile and angular velocity of the swing arm actuator are very important parameters for the design of L/UL system to avoid collision between slider and disk.

Base Structure Design of Laptop HDD for Anti-Shock Performance (내충격 성능 향상을 위한 랩탑 하드디스크의 베이스 설계)

  • Lim, Seung-Ho;Park, No-Cheol;Park, Young-Pil;Park, Kyoung-Su;Seol, Woong;Kim, Kyung-Tae
    • Transactions of the Society of Information Storage Systems
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    • v.5 no.2
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    • pp.76-81
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    • 2009
  • Mobile devices have become an important part of daily life. This is especially true of laptop PCs, which are portable enough to be used almost anywhere. Laptop PCs, however, cannot be nomadic if each component is not robust enough to endure rugged laptop operating environment. Generally, external shock makes collision on head-disk interface and damage to read-write performance. To minimize the likelihood of failure, shock analysis must be incorporated into the design of hard disk drive in laptop. This research explores the structure modification of laptop HDD base, for improving shock performance using finite element analysis which considers the flexibility of whole HDD structure. FE model is verified by modal test and finely tuned. Then we obtained the transmitted acceleration of spindle and pivot and the relative displacement between disk and slider head as shock response. Based on shock simulation, the structural dynamics modification is performed and the primary design parameters are extracted.

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An Experimental Study on the Frictional Behavior of Silver Coating Films at Sliding Surfaces (은 박막의 미끄럼 마찰거동에 대한 실험적 고찰)

  • 양승호;공호성;윤의성;김대은
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.06a
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    • pp.7-13
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    • 1999
  • An experimental study was performed to discover the effect of silver coating on the frictional behavior of SM45C steel at sliding surfaces. Pure silver was coated the SM45C disk surfaces by a thermal evaporation method. Experiments using a pin-on-disk test-rig was performed under dry air and various humidity conditions. Friction coefficients increased to a high and unstable value after failure of coating, and friction coefficients increased with increasing the thickness of silver coated layer. But optimum coating thickness was not observed.

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Recovery Methods in Main Memory DBMS

  • Kim, Jeong-Joon;Kang, Jeong-Jin;Lee, Ki-Young
    • International journal of advanced smart convergence
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    • v.1 no.2
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    • pp.26-29
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    • 2012
  • Recently, to efficiently support the real-time requirements of RTLS( Real Time Location System) services, interest in the main memory DBMS is rising. In the main memory DBMS, because all data can be lost when the system failure happens, the recovery method is very important for the stability of the database. Especially, disk I/O in executing the log and the checkpoint becomes the bottleneck of letting down the total system performance. Therefore, it is urgently necessary to research about the recovery method to reduce disk I/O in the main memory DBMS. Therefore, In this paper, we analyzed existing log techniques and check point techniques and existing main memory DBMSs' recovery techniques for recovery techniques research for main memory DBMS.

Effect of Disk Material on the Performance of Cermet Tipped Circular Saw (서멧팁 은납형 둥근톱의 성능에 미치는 기판의 영향)

  • Lee Jae-Woo
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.350-353
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    • 2005
  • It is a feature of primary importance for a backing material for circular saw blades having teeth which are tipped with cermet, that the steel has not a too high hardenability in order that the backing material shall not be completely hardened through brazing, welding or grinding, etc. in connection with the finishing operation in the manufacturing of circular saw blade. It is believed that V-(2Mo+W) added steel from this point of view had best conditions. Using V-(2Mo+W) added backing steel, the tool failure can be effectively prevented due to superior damping performance.

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Development of a Diagnostic Algorithm with Acoustic Emission Sensors and Neural networks for Check Valves

  • Seong, Seung-Hwan;Kim, Jung-Soo;Hur, Seop;Kim, Jung-Tak;Park, Won-Man
    • Nuclear Engineering and Technology
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    • v.36 no.6
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    • pp.540-548
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    • 2004
  • Check valve failure is one of the worst problems in nuclear power plants. Recently, many researches have been based on new technology using accelerometers and ultrasonic and magnetic flux detection have been carried out. Here, we have suggested a method that uses acoustic emission sensors for detecting the failures of check valves through measuring and analyzing backward leakage flow, a system that works without disassembling the check valve. For validating the suggested acoustic emission sensor methodology, we designed a hydraulic test loop with a check valve. We have assumed in this study that check valve failure is caused by disk wear or by the insertion of a foreign object. In addition, we have developed diagnostic algorithms by using a neural network model to identify the type and size of the failure in the check valve. Our results show that the proposed diagnostic algorithm with acoustic emission sensors is a good solution for identifying check valve failure without necessitating any disassembly work.

The Accelerated Life Test of 2.5 Inch Hard Disk In The Environment of PC using (PC 사용 환경의 2.5 인치 하드디스크의 가속 수명 시험)

  • Cho, Euy-Hyun;Park, Jeong-Kyu;Seo, Hui-Don
    • Journal of Digital Contents Society
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    • v.15 no.1
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    • pp.19-27
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    • 2014
  • In order to estimate the life of 2,5 inch HDD which is adopted by PC environment, make the test plan which reflect the failure mode of market, make the test model of accelerated life test which reflect the stress of temperature. after an analysis of the environment of PC using, test procedure was decided that operation was write 50 % and read 50 %, and then access method was sequential 50 % and random 50%. The acceleration life test was executed on condition that temperature was $50^{\circ}C$ and $60^{\circ}C$, performance was 95 % in max performance, test time was 1000 hours. by the test of goodness of fit of anderson-darling of the failure data during test, it was confirmed that the distribution of failure fellow weibull. test for shape and scale was equal, and shape parameter was 0.7177, characteristic life was 429434 hours at normal user condition($30^{\circ}C$) by the analysis of weibull-arrhenius modeling. It made no difference about the statistics when equality test was executed. The activation energy was 0.2775eV. In analyzing between the failure samples of acceleration test and the samples of market return even though there is detail difference about the share of failure mode, the rank of share was almost same. This study suggest the test procedure of acceleration test of 2.5 inch HDD in PC using environment, and help the life estimation at manufacture and user.