Lecture_20 - Chapter 6 Storage and Other I/O Topics Chapter...

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Unformatted text preview: Chapter 6 Storage and Other I/O Topics Chapter 6 Storage and Other I/O Topics 2 Introduction I/O devices can be characterized by Behaviour: input, output, storage Partner: human or machine Data rate: bytes/sec, transfers/sec I/O bus connections 6.1 Introduction Chapter 6 Storage and Other I/O Topics 3 I/O System Characteristics Dependability is important Particularly for storage devices Performance measures Latency (response time) Throughput (bandwidth) Desktops & embedded systems Mainly interested in response time & diversity of devices Servers Mainly interested in throughput & expandability of Chapter 6 Storage and Other I/O Topics 3 I/O System Characteristics Dependability is important Particularly for storage devices Performance measures Latency (response time) Throughput (bandwidth) Desktops & embedded systems Mainly interested in response time & diversity of devices Servers Mainly interested in throughput & expandability of devices Chapter 6 Storage and Other I/O Topics 4 Dependability Fault: failure of a component May or may not lead to system failure 6.2 Dependability, Reliability, and Availability Service accomplishment Service delivered as specified Service interruption Deviation from specified service Failure Restoration Chapter 6 Storage and Other I/O Topics 5 Dependability Measures Reliability: mean time to failure (MTTF) Service interruption: mean time to repair (MTTR) Mean time between failures MTBF = MTTF + MTTR Availability = MTTF / (MTTF + MTTR) Improving Availability Increase MTTF: fault avoidance, fault tolerance, fault forecasting Reduce MTTR: improved tools and processes for diagnosis and repair Chapter 6 Storage and Other I/O Topics 6 Disk Storage Nonvolatile, rotating magnetic storage 6.3 Disk Storage Chapter 6 Storage and Other I/O Topics 7 Disk Sectors and Access Each sector records Sector ID Data (512 bytes, 4096 bytes proposed) Error correcting code (ECC) Used to hide defects and recording errors Synchronization fields and gaps Access to a sector involves...
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This note was uploaded on 03/07/2012 for the course CS 2506 taught by Professor Srinidhivaradarajan during the Spring '12 term at Virginia Tech.

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Lecture_20 - Chapter 6 Storage and Other I/O Topics Chapter...

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