Browse Prior Art Database

A Method and System for Using Application Scores to Elect a Leader for Replicated Services

IP.com Disclosure Number: IPCOM000215882D
Publication Date: 2012-Mar-14
Document File: 5 page(s) / 66K

Publishing Venue

The IP.com Prior Art Database

Related People

Flavio Junqueira: INVENTOR [+3]

Abstract

A method and system for using application scores to elect a leader for replicated services is disclosed. The method and system uses an algorithm to select leader for replicated services.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 23% of the total text.

A Method and System for Using Application Scores to Elect a Leader for Replicated Services

Abstract

A method and system for using application scores to elect a leader for replicated services is disclosed.  The method and system uses an algorithm to select leader for replicated services.

Description

Disclosed is a method and system for using application scores to elect a leader for replicated services.  The method and system provides an algorithm that takes the application scores as input and uses the application scores to arrange servers in a particular sequence during election.  The algorithm provides the ability of selecting desired properties of a leader server to an application.  The leader server corresponds to a server that has the highest application score.  An application specific scoring function is implemented in a module.  Before starting leader election, a local algorithm module of a server queries the module in which the application specific scoring function is implemented.  The module computes scores based on information collected during regular operation or by computing measurements for estimating performance.  After querying the module, servers share their scores and elect a server with highest score as the leader server.  Thereafter, the method and system uses a consensus service through which the leader server sends requests to a quorum of servers, the quorum of servers log the requests and responds to the leader server.  Subsequently, the leader server commits the request and sends an acknowledgement to the servers upon receiving the response from the quorum of servers. The other serves commit upon receiving the acknowledgement from the leader.

The application specific scoring function is a function that maps identifiers of servers to scores.  The application specific scoring function is based on two metrics - recovery time and latency of requests perceived by clients.  In wide area settings, links may have different latencies.

In an exemplary embodiment, three servers may be deployed in two data centers D1 and D2.  Let δD be the latency of the links between a server in D1 and a server in D2.  In the wide area setting, the link latency inside a data center is lower than the link latency between two data centers.

Fig. 1 illustrates the three servers deployed in the two data centers D1 and D2.  As shown in fig. 1, p1 and p2 represent server in data center D1 and p3 represent server in data center D2.

Figure 1

In another exemplary embodiment, when a server is elected as the leader server, latency of links can be represented as δi.  The server then acknowledges a request to a client only after a quorum of servers accepts the request.  The quorum of servers accepts the request by logging in to storage and then responding to the request.

Fig. 2 illustrates the link between the server elected as the leader server and other servers with respective latencies.  As shown in fig. 2, p1 represents the leader server a...