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Balraj Kumar, Lovely Professional University Unit 11: Recovery System

Unit 11: Recovery System Notes

CONTENTS

Objectives
Introduction

11.1 Introduction to Crash Recovery
11.1.1 Stealing Frames and Forcing Pages

11.1.2 Recovery - Related Steps during Normal Execution
11.1.3 Overview of ARIES

11.2 Failure Classification
11.3 Storage Structure

11.4 Recovery and Atomicity
11.5 Log Based Recovery

11.6 Recovery with Concurrent Transactions
11.7 Buffer Management

11.8 Failure with Loss of Non-volatile Storages
11.9 Summary

11.10 Keywords
11.11 Self Assessment

11.12 Review Questions
11.13 Further Readings

Objectives

After studying this unit, you will be able to:
 Realise the concept of crash recovery
 Discuss recovery and atomicity
 Explain log based recovery
 State the concept of buffer management

Introduction

The database system must take actions in advance to ensure that the atomicity and durability
properties of transactions as a computer system, like any other device, is subject to failure from
a variety of causes: disk crash, power outage, software error, a fire in the machine room, even
sabotage. In any failure, information may be lost. Are preserved. An integral part of a database
system is a recovery scheme that can restore the database to the consistent state that existed

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