Distributed Systems

Distributed Systems

1. Tecnológico de Costa Rica, Carrera: Ingeniería en Computación, Sede: Cartago, Curso: Principios de sistemas operativos, Profesor: Esteban Arias Méndez, Estudiante: Jason David Espinoza Siles, Carné: 201223941, II semestre, 2016, Libro: Operating System Concepts 9th.pdf capítulo 17

2. Distributed system is collection of loosely coupled processors interconnected by a communications network

3. Network-Operating Systems

   • Users are aware of multiplicity of machines  Access to resources of various machines is done explicitly by:  Remote logging into the appropriate remote machine (telnet, ssh)  Remote Desktop (Microsoft Windows)  Transferring data from remote machines to local machines, via the File Transfer Protocol (FTP) mechanism  Users must change paradigms – establish a session, give network-based commands  More difficult for users

4. Distributed-Operating Systems

   • Users not aware of multiplicity of machines  Access to remote resources similar to access to local resources  Data Migration – transfer data by transferring entire file, or transferring only those portions of the file necessary for the immediate task  Computation Migration – transfer the computation, rather than the data, across the system  Via remote procedure calls (RPCs)  or via messaging system

5. Routing Strategies

   • Fixed routing - A path from A to B is specified in advance; path changes only if a hardware failure disables it  Since the shortest path is usually chosen, communication costs are minimized  Fixed routing cannot adapt to load changes  Ensures that messages will be delivered in the order in which they were sent  Virtual routing- A path from A to B is fixed for the duration of one session. Different sessions involving messages from A to B may have different paths  Partial remedy to adapting to load changes  Ensures that messages will be delivered in the order in which they were sent

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