Distributed Systems

CHAPTER 16: DISTRIBUTED-SYSTEM STRUCTURES

Network-Operating Systems

Distributed-Operating Systems

Remote Services

Robustness

Design Issues

Operating System Concepts, Addison-Wesley © 1994

Silberschatz & Galvin © 1994

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.

Transferring data from remote machines to local

machines, via the File Transfer Protocol (FTP)

mechanism.

Operating System Concepts, Addison-Wesley © 1994

16.1

Silberschatz & Galvin © 1994

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.

Process Migration − execute an entire process, or

parts of it, at different sites.

- Load balancing − distribute processes across

network to even the workload.

- Computation speedup − subprocesses can run

concurrently on different sites.

- Hardware preference − process execution may

require specialized processor.

- Software preference − required software may

be available at only a particular site.

- Data access − run process remotely, rather than

transfer all data locally.

Operating System Concepts, Addison-Wesley © 1994

16.2

Silberschatz & Galvin © 1994

Remote Services

Requests for access to a remote file are delivered

to the server. Access requests are translated to

messages for the server, and the server replies are

packed as messages and sent back to the user.

A common way to achieve this is via the Remote

Procedure Call (RPC) paradigm.

Messages addressed to an RPC daemon listening

to a port on the remote system contain the name

of a...