After studying this chapter, you should be able to: Discuss basic concepts related to concurrency, such as race conditions, OS concerns, and mutual exclusion requirements; understand hardware approaches to supporting mutual exclusion; define and explain semaphores; define and explain monitors. | Module 15: Network Structures Background Motivation Topology Network Types Communication Design Strategies Operating System Concepts Node Types Mainframes (IBM3090, etc.) example applications: airline reservations banking systems many large attached disks Workstations (Sun, Apollo, Microvax, RISC6000, etc.) example applications: computer-aided design office-information systems private databases zero, one or two medium size disks Operating System Concepts Nodes Types (Cont.) Personal Computers example applications: office information systems small private databases zero or one small disk Operating System Concepts A Distributed System Operating System Concepts Motivation Resource sharing sharing and printing files at remote sites processing information in a distributed database using remote specialized hardware devices Computation speedup – load sharing Reliability – detect and recover from site failure, function transfer, reintegrate failed site Communication – message passing . | Module 15: Network Structures Background Motivation Topology Network Types Communication Design Strategies Operating System Concepts Node Types Mainframes (IBM3090, etc.) example applications: airline reservations banking systems many large attached disks Workstations (Sun, Apollo, Microvax, RISC6000, etc.) example applications: computer-aided design office-information systems private databases zero, one or two medium size disks Operating System Concepts Nodes Types (Cont.) Personal Computers example applications: office information systems small private databases zero or one small disk Operating System Concepts A Distributed System Operating System Concepts Motivation Resource sharing sharing and printing files at remote sites processing information in a distributed database using remote specialized hardware devices Computation speedup – load sharing Reliability – detect and recover from site failure, function transfer, reintegrate failed site Communication – message passing Operating System Concepts Topology Sites in the system can be physically connected in a variety of ways; they are compared with respect to the following criteria: Basic cost. How expensive is it to link the various sites in the system? Communication cost. How long does it take to send a message from site A to site B? Reliability. If a link or a site in the system fails, can the remaining sites still communicate with each other? The various topologies are depicted as graphs whose nodes correspond to sites. An edge from node A to node B corresponds to a direct connection between the two sites. The following six items depict various network topologies. Operating System Concepts Fully connected network Partially connected network Operating System Concepts Tree-structured network Star network Operating System Concepts Ring networks: (a) Single links. (b) Double links Operating System Concepts Bus network: (a) Linear bus. (b) Ring bus. Operating System Concepts Network Types :Local-Area Network .
