Book Image

Oracle Database 11g : Underground Advice for Database Administrators

By : April Sims
Book Image

Oracle Database 11g : Underground Advice for Database Administrators

By: April Sims

Overview of this book

Today DBAs are expected to deploy and manage large databases with quality service and little to no downtime. The DBA's main focus is on increasing productivity and eliminating idle redundancy throughout the enterprise. However, there is no magic set of best practices or hard and fast rules that DBAs need to follow, and this can make life difficult. But if DBAs follow some basic approaches and best practices, tasks can be performed more efficiently and effectively.This survival guide offers previously unwritten underground advice for DBAs. The author provides extensive information to illuminate where you fit in, and runs through many of the tasks that you need to be watchful of, extensively covering solutions to the most common problems encountered by newcomers to the world of Oracle databases.The book will quickly introduce you to your job responsibilities, as well as the skills, and abilities needed to be successful as a DBA. It will show you how to overcome common problems and proactively prevent disasters by implementing distributed grid computing—scalable and robust—with the ability to redeploy or rearchitect when business needs change. Reduce downtime across your enterprise by standardizing hardware, software, tools, utilities, commands, and architectural components.This book will also help you in situations where you need to install Oracle Database 11g or migrate to new hardware making it compliant with a Maximum Availability Architecture. By the end of this book you will have learned a lot and gained confidence in your abilities. You will be armed with knowledge as to which tools are best used to accomplish tasks while proactively moving towards an automated environment.
Table of Contents (14 chapters)
Oracle Database 11g—Underground Advice for Database Administrators
Credits
About the author
About the reviewers
Preface
Index

Corruption detection


There are several types of database corruptions that can cause extensive data loss if due diligence is not taken to prevent it from happening in the first place:

  • Datafile block corruption—physical or logical

  • Table/index inconsistency

  • Extents inconsistencies

  • Data dictionary inconsistencies

Physical corruption

Physical corruption is most often caused by defective memory boards, power disruption, I/O controller problems, or broken sectors on a hard disk drive. A defective physical component prevents the complete write to the data block, which also includes the accompanying update to the header block. You may have block corruption, but the database will appear to operate normally because reads usually don't have an issue but writes will report the corruption error as something similar to the following:

ORA-01578:
ORACLE data block corrupted (file # string, block # string)

Don't always expect issues such as corruption to show up in an obvious way. While doing testing for this chapter...