Lesson 1 Flashcards
(19 cards)
What is fault tolerance in distributed systems?
Fault tolerance is achieved by recovery and redundancy.
Fault tolerance ensures that distributed systems maintain availability even with low hardware/software/network reliability.
What does transparency in distributed systems mean?
Distributed systems should be perceived as a whole rather than a collection of components.
Transparency has different dimensions, representing various properties that distributed systems should have.
How is scalability defined in the context of distributed systems?
Scalability is the adaptation of distributed systems to accommodate more users and respond faster.
Usually achieved by adding more and/or faster processors.
What is the importance of openness in distributed systems?
Openness is concerned with extensions and improvements of distributed systems, requiring detailed interfaces to be published.
New components must integrate with existing ones, resolving differences in data representation.
What is concurrency in distributed systems?
Concurrency refers to components executing in concurrent processes, accessing and updating shared resources.
Integrity may be violated if concurrent updates are not coordinated.
What does access transparency enable in distributed systems?
Access transparency enables local and remote information objects to be accessed using identical operations.
Examples include file system operations in NFS and SQL queries.
What is location transparency?
Location transparency allows information objects to be accessed without knowledge of their location.
Examples include file system operations in NFS and tables in distributed databases.
What is concurrency transparency?
Concurrency transparency enables several processes to operate concurrently using shared information objects without interference.
Examples include NFS and database management systems.
What is replication transparency?
Replication transparency allows multiple instances of information objects to be used without user knowledge of the replicas.
Examples include distributed DBMS and mirroring web pages.
What is failure transparency in distributed systems?
Failure transparency conceals faults, allowing users to complete tasks despite component failures.
An example is a database management system.
What does migration transparency allow in a distributed system?
Migration transparency allows the movement of information objects within a system without affecting user operations.
Examples include NFS and web pages.
What is performance transparency?
Performance transparency allows the system to be reconfigured to improve performance as loads vary.
An example is a distributed make.
What is scaling transparency?
Scaling transparency allows systems and applications to expand in scale without changes to structure or algorithms.
Examples include the World-Wide-Web and distributed databases.
What is resource sharing in distributed systems?
Resource sharing is the ability to use any hardware, software, or data anywhere in the system.
A resource manager controls access and concurrency.
What defines a distributed system?
A distributed system is a collection of autonomous computer systems that are connected by a centralized network and distributed system software.
They communicate by sharing resources and performing assigned tasks.
What are the common characteristics of distributed systems?
Common characteristics include:
* Resource Sharing
* Openness
* Concurrency
* Scalability
* Fault Tolerance
* Transparency
What distinguishes centralized systems from distributed systems?
Centralized systems have one component with non-autonomous parts, while distributed systems consist of multiple autonomous components.
Centralized systems have a single point of control and failure, while distributed systems have multiple points.
What are examples of distributed systems?
Examples include:
* Telecommunication networks
* Computer networks like the Internet
* Wireless sensor networks
* Distributed databases and management systems
What are distinguishing features of multiprocessors and multicomputers?
Distinguishing features include:
* Private vs shared memory
* Bus vs switched interconnection
