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

What does RMAN backup, restore, and recover?


Did you notice the addition of the word "restore" in the title of this section? Hopefully you did, as there is an important difference between restore and recover when it comes to Oracle. Restore is putting back the copy of the object (datafile, controlfile, spfile, archivelog) to a specific location. Recover is applying all of the transactions located in the online or offline (archived) redo and online undo segments to bring the database to a consistent state.

Consistency is where the checkpoint change numbers, for all datafiles agree with the checkpoint SCN of the database. That is your basic goal when doing database recovery. It is important to remember because anything that interrupts this process may result in lost transactions. Consistency is also important for the controlfile (it has its own checkpoint SCN), as Oracle takes a snapshot (read-consistent) of the controlfile if you back up the database when it is either mounted or open. The...