Introduction to DB2 9 database recovery

Introduction to DB2 9 database recovery - Introduction to...

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Introduction to DB2 9 database recovery Recovery scenarios Skill Level: Intermediate Amol D. Barsagade ( amolbarsagade@in.ibm.com ) Database Consultant IBM 16 Aug 2007 A tried and tested backup and recovery strategy is essential in preventing data loss. A database can encounter any number of problems, including power interruptions, storage media failure, and application crashes. Each of these can result in a database failure and each failure requires a different recovery action. This tutorial introduces the backup and recovery capabilities in IBM® DB2® for Linux®, UNIX® and Windows®. In addition, it presents a step-by-step approach showing how to recover data in various failure scenarios. Section 1. Before you start About this tutorial Global support organizations are based on customer service and satisfaction. As such, protecting against failures is a huge challenge for the database administrator. In production or 24 X 7 environments, where databases are mission critical, any data loss is unacceptable. Therefore, it is vital to understand the different data recovery options offered by a database management system (DBMS) as well as have a data recovery plan in place that implements them. Objectives This tutorial introduces various DB2 9 recovery options and covers the following topics: Introduction to DB2 9 database recovery © Copyright IBM Corporation 1994, 2008. All rights reserved. Page 1 of 20
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• Database logging • How to change the database logging mode • Best practices to keep database data safe • How to recover an entire database after a failure • How to recover when a table space container gets dropped or corrupted • How to recover a table that is dropped by accident • How to recover to a specific point-in-time Section 2. Database logging DB2 databases support two different logging modes: Circular and Archival . When a new database is created, circular logging is the default. If the business need requires something more advanced, you can change the logging mode from circular to archival. A summary of transaction logging in DB2 A transaction is a logical unit of work. Every transaction has corresponding log records that are stored in transaction log files. Every transaction has a corresponding entry in what is called the Redo Log . Redo log entries are written to the current active log file. When the active log file becomes full, it is marked as unavailable , at which point DB2 makes the next log file in the sequence the active log file and continues writing log entries into it. This cycling process is repeated as the current active log file becomes full. When transactions are completed (a COMMIT or ROLLBACK statement is issued), the corresponding log entries are released, since they are no longer needed to recover the database. DB2 always tries to write log entries into the set of primary log files, that is, the log
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This note was uploaded on 02/11/2011 for the course IT 232 taught by Professor Drehr during the Spring '11 term at NJIT.

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Introduction to DB2 9 database recovery - Introduction to...

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