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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...