1. The Overall Story Flashcards Preview

COMP18112 - Distributed Systems > 1. The Overall Story > Flashcards

Flashcards in 1. The Overall Story Deck (18)
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1
Q

Why Distribute?

A

Functional Reasons: doing things we cant on centralised ones

Non Functional: so we can do the same things but better, faster etc.

2
Q

What is Distributed System?

A

collection of cooperating systems connected through an interconnect cooperating on the solution of a problem

3
Q

Why do challenges arise?

A

Coordination. keeping everyone on schedule, communication is costly and unreliable. each component is autonomous and cant be completely known

4
Q

Why is the network so difficult to handle?

A

Communication channels fail unpredictably. Interconnections are problematic

5
Q

What must DS deliver?

A

Distribution Transparency. Behave to the user as a centralised system

6
Q

How do Internet, Web and eMail fit into the landscape?

A

Show the need for high level naming and addressing

Show the consequences of the need to maintain state or not

reliability, scalability, response time, soundness

Demonstrate competition leading to contention, replication and consistency

7
Q

How did system software evolve to modern DSs?

A

Mainframes -> Personal Computers -> Mobile devices

8
Q

What is a centralised system?

A

Uses a single processor to multi-task to give the illusion of concurrency. Threaded

9
Q

What is a parallel system?

A

A Multi-processor system

10
Q

What is an Interconnect?

A

Connection between devices of networks

11
Q

How do we abstract the interconnect in software?

A

Protocol stacks.

12
Q

What architectural paradigms for DS are there?

A

Shared state and Message Passing

13
Q

How is Message Passing implemented?

A

Direct communication or remote procedure calls

14
Q

How do OS support and underpin the design of large scale interconnects?

A

take charge of communication evens by synchronising transfers, blocking thread of execution.

or provide generic abstractions such as ports or sockets over which high level protocols can be more easily built

15
Q

What are some classical distributed algorithms?

A

Competition, Contention, deadlock
Clock synchronisation
Leader election, Two-phase commit for transactional processing

16
Q

How does file sharing illustrate issues, challenges and solutions in modern DS?

A

Illustrates possibilities for resilience, scalability and availability in the light of replication.

17
Q

How does muli-player gaming illustrate issues, challenges and solutions in DS?

A

In spite of immense computing power, distributed techniques are crucial to preserving the illusion of a single shared timeline

18
Q

How do we process 2 billion pages fast over and over?

A

Massively distributed systems achieve great scale out. Map reduce is the foundation for processing tasks with big data