Hierarchical quorum consensus a new algorithm for managing replicated data
Download
1 / 21

Hierarchical Quorum Consensus: A New Algorithm for Managing Replicated Data - PowerPoint PPT Presentation


  • 114 Views
  • Uploaded on

Hierarchical Quorum Consensus: A New Algorithm for Managing Replicated Data . Akhil Kumar IEEE TRANSACTION ON COMPUTERS, VOL.40, NO.9, SEPTEMBER 1991. Outline. Introduction Quorum Consensus Algorithm Hierarchical Quorum Consensus HQC algorithm Availability Analysis

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Hierarchical Quorum Consensus: A New Algorithm for Managing Replicated Data ' - raiden


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Hierarchical quorum consensus a new algorithm for managing replicated data

Hierarchical Quorum Consensus: A New Algorithm for Managing Replicated Data

Akhil Kumar

IEEE TRANSACTION ON COMPUTERS, VOL.40, NO.9, SEPTEMBER 1991


Outline
Outline Replicated Data

  • Introduction

  • Quorum Consensus Algorithm

  • Hierarchical Quorum Consensus

  • HQC algorithm

  • Availability Analysis

  • Tradeoffs between HQC and Related Algorithm

  • Conclusion


Introduction 1 8
Introduction(1/8) Replicated Data

  • Motivations of Data Replication

    • Fault Tolerant

    • Increasing System Reliability


Introduction 2 8

:One copy of an object Replicated Data

Introduction(2/8)

1.Providing Fault tolerant capability in distributed system


Introduction 3 8

The copy is using Replicated Data

:One copy of an object

Introduction(3/8)

2.Replication of data for concurrent read/write

The copy is using


Introduction 4 8
Introduction(4/8) Replicated Data

  • Two problems occur in distribution system:

    • RW problem

    • WW problem

Write

Read

Read

Write

Write

Write


Introduction 5 8

Two operations of quorum structure in distribution system: Replicated Data

Read operation

To access all of the copies in a read quorum

a copy with the highest version number is returned

Write operation

To write to all of the copies in a write quorum

assigns each copy the version number that is one more than the maximum version number encountered in the write quorum.

Introduction(5/8)

Read quorum

Write quorum


Introduction 6 8

Read and Write Replicated Data

Write and Write

Read quorum

write quorum

Write quorum

Write quorum

Introduction(6/8)

  • The solution : intersect property of read/write quorum

    • RW problem

    • WW problem


Introduction 7 8
Introduction(7/8) Replicated Data

  • This paper generalizes the quorum consensus scheme (QC)

    • into a multilevel algorithm called hierarchical quorum consensus (HQC)

    • shows that given a collection of n copies of an object, the minimum size of a quorum is n0.63 copies.

  • A smaller quorum size results in a lower cost of synchronization.


Introduction 8 8
Introduction(8/8) Replicated Data

  • Our method is based on organizing the copies of an object into

    • extending the quorum consensus algorithm

    • Logical node

    • multilevel hierarchy


Qc algorithm

8 copies let n=8+1 Replicated Data

qr+qw > 9

2qw > 9

5 5

4 6

. .

. .

9 copies let n=9+1

qr+qw > =10

2qw > =10

5 5

4 6

. .

. .

Read and Write

Read quorum

Write quorum

The quorum intersection conditions:

Read and Write

Read quorum

Write quorum

QC Algorithm


The concept of hqc

best size Replicated Data

The concept of HQC

  • An example of 2-level

    l1=3 l2=3

    r1+w1>3 r2+w2>3

    2w1>3 2w2>3

    2 2 2 2 4 4

    1 3 1 3 1 9

    1 3 2 2 2 6

    r w


The concept of hqc1
The concept of HQC Replicated Data


Hqc algorithm
HQC algorithm Replicated Data

For example:

l1=3

r1+w1>3

2w1>3

2 2

1 3


Hqc algorithm1
HQC algorithm Replicated Data


Hqc algorithm2
HQC algorithm Replicated Data

=


Hqc algorithm3
HQC algorithm Replicated Data

best size

worst size


Availability analysis

HQC Replicated Data  Majority Voting

HQC Majority Voting

Majority Voting

Majority Voting

HQC

HQC

Availability Analysis


Availability analysis1

HQC Replicated Data  Majority Voting

HQC Majority Voting

Majority Voting

Majority Voting

HQC

HQC

Availability Analysis


Tradeoffs between hqc and related algorithm
Tradeoffs between HQC and Related Algorithm Replicated Data

HQC is better than others fully.


Conclusion
Conclusion Replicated Data

  • In this paper, they introduced a new algorithm, also based on voting, and showed that:

    • It is possible to reduce the size of a quorum from (n+1)/2copies (as in majority voting) to n0.63 copies

    • The HQC method produces certain intersecting sets of quorums that cannot be produced in a single-level vote assignment


ad