PPT-CS 5204

Operating Systems Godmar Back Disks amp File Systems CS 5204 Fall 2015 Filesystems Consistency amp Logging CS 5204 Fall 2015 Filesystems amp Managing Faults Filesystems promise Persistence. A Consensus Algorithm for . Fault Tolerant Replication. CS 5204 – Fall, 2008. System Model. Messages. possible indefinite delay. possible duplication or loss. delivered messages not corrupted. . . .. . Asynchronous . Meta-Data Protection in File System. . Authors . - Margo Seltzer, Gregory Ganger et all. . Presenter – Abhishek Abhyankar . . MS Computer Science Virginia Tech. CS5204 – Operating Systems. 1. CS 5204 – Operating Systems. 2. Communicating Sequential Processes (CSP). single thread of control . autonomous . encapsulated . named . static . synchronous . reliable . The Global State Recording Algorithm. CS 5204 – Operating Systems. 2. The Model. Node properties . No shared memory . No global clock . node. channel. Channel properties: . FIFO . loss free . non­duplicating. CS5204 – Operating Systems. 1. CS 5204 – Operating Systems. 2. Fault Tolerance. erroneous state. error. valid state. failure. causes. fault. leads to. recovery. An error is a manifestation of a fault that can lead to a failure.. Distributed Storage. 1. Dennis Kafura – CS5204 – Operating Systems. CS 5204 – Operating Systems. 2. Peer-to-Peer Systems. Definition. : “Peer-to-peer systems can be characterized as distributed systems in which all nodes have identical capabilities and responsibilities, and all communication is symmetric.” –. Maurice Herlihy (DEC), J. Eliot & B. Moss (UMass). Presenter: Mariano Diaz. CS 5204 – Fall, 2009. Part 1: Concepts and Hardware-based Approaches. Introduction. What’s a transaction?. Transaction: a finite sequence of machine instructions, executed by a single process, that satisfies the following:. CS5204 – Operating Systems. 1. CS 5204 – Operating Systems. 2. Fault Tolerance. erroneous state. error. valid state. failure. causes. fault. leads to. recovery. An error is a manifestation of a fault that can lead to a failure.. Security Policy Assertion Language. CS5204 – Operating Systems. 1. CS 5204 – Operating Systems. 2. The Grid. Resources and user belong to a variety of different independent organizations. Resources and users are connected via communication networks. Dennis Kafura - CS 5204 - Operating Systems. 1. Dennis Kafura - CS 5204 - Operating Systems. 2. Reasons for Concurrency. multitasking. parallelism. performance. coordination. Moore’s Law. Dennis Kafura - CS 5204 - Operating Systems. Respirable. Crystalline Silica. Mariano Kramer, Associate Cal OSHA Safety Engineer. Cal OSHA Update. November 4, 2016. Status of Final Rule. Horcher. rulemaking procedure. Adopted by California Occupational Safety and Health Board – September 2016 . 1. CS 5204 – Operating Systems. 2. Fault Tolerance. erroneous state. error. valid state. failure. causes. fault. leads to. recovery. An error is a manifestation of a fault that can lead to a failure.. Fault Tolerant Replication. CS 5204 – Fall, 2008. System Model. Messages. possible indefinite delay. possible duplication or loss. delivered messages not corrupted. . . .. replicas. client. Replicas. CS5204 – Operating Systems. 1. CS 5204 – Operating Systems. 2. A Process with Alternative Behavior. A vending machine that dispenses chocolate candies allows either a 1p (p for pence) or a 2p coin to be inserted. After inserting a 1p coin, a button labelled “little” may be pressed and the machine will then dispense a small chocolate. After inserting a 2p coin, the “big” button may be pressed and the machine will then dispense a large chocolate. The candy must be collected before additional coins can be inserted. .