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Distributed Systems ETH 2020

Distributed Systems Lecture ETH 2020

Distributed Systems Lecture ETH 2020


Set of flashcards Details

Flashcards 129
Language English
Category Electrical Engineering
Level University
Created / Updated 15.01.2021 / 20.01.2024
Licencing Not defined
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What is a ticket and what properties does it have?

A ticket is a weaker form of a lock with the following properties:

  1. reissuable: server can issue more tickets even if previous ones not yet returned
  2. expiration: server only accepts most recently issued ticket

What does the Paxos Protocol look like?

a message propose(t,c) is chosen if it is stored by a majority of servers

 

if a command c is executed by some servers, all servers eventually execute c

Define consensus and name its properties.

There are n nodes of which at most f might crash (n-f correct). Node i starts with an input value v_i. The nodes must decide for one of those values satisfying the following properties:

  1. agreement: all correct nodes decide for the same value
  2. termination: all correct nodes terminate in finite time
  3. validity: the decision must be an input value of a node

Define configuration and critical configuration.

  • We say that a system is fully defined (at any point during the execution) by its configuration C. The configuration includes the state of every node, and all messages that are in transit (sent but not yet received).
  • C is critical if C is bivalent but all configurations that are direct children of C are univalent