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Oracle Database 12c Backup and Recovery Survival Guide

Chapter 1. Understanding the Basics of Backup and Recovery

The constant evolution of IT has, among other things, affected the role of a database administrator (DBA). Today the DBA is not merely a Database Administrator anymore, but is morphing more into the Database Architect role. If you want to become a successful DBA and be more competitive in the market, you should have a different skill set than what was normally required in the past. You need to have a wide range of understanding in architectural design, network, storage, licensing, and much more. The more knowledge you have, the better opportunities you will find.

The main idea of this chapter is to introduce you to some basic concepts regarding backup and recovery, giving you a general overview of the most important methods and tools available for you to achieve your backup goals. Therefore, in this chapter, we will cover the following topics:

Understanding the need for creating backups
Getting familiar with the different backup types
An overview of backup strategy
Understanding what is redo and how it affects your database recoverability
Understanding database operational modes and redo generation

Purpose of backup and recovery

As a DBA, you are the person responsible for recovering the data and guarding the business continuity of your organization. Consequently, you have the key responsibility for developing, deploying, and managing an efficient backup and recovery strategy for your institution or clients that will allow them to easily recover from any possible disastrous situation. Remember, data is one of the most important assets a company can have. Most organizations would not survive after the loss of this important asset.

Testing backups

It's incredible how many corporations around the world do not have a proper disaster recovery plan (DRP) in place, and what is worse, many DBAs never even test their backups. Most of the time when auditing Oracle environments for clients, I ask the following question to the DBA team:

Are you 100 percent sure that you can trust your backups? For this question I generally receive answers like:
- I'm not 100 percent sure since we do not recover from backups too often
- We do not test our backups, and so I cannot guarantee the recoverability of them

Another good question is the following:

Do you know how long a full recovery of your database will take? Common responses to this question are:
- Probably anything between 6 and 12 hours
- I don't know, because I've never done a full recovery of my database

As you can see, a simple implementation of a procedure to proactively test the backups randomly will allow you to:

Test your backups and ensure that they are valid and recoverable: I have been called several times to help clients because their current backups are not viable. Once I was called to help a client and discovered that their backup-to-disk starts every night at 10 P.M. and ends at 2 A.M. Afterwards, the backup files are copied to a tape by a system administrator every morning at 4 A.M. The problem here was that when this process was implemented, the database size was only 500 GB, but after few months, the size of the database had grown to over 1 TB. Consequently, the backup that was initially finishing before 2 A.M. was now finishing at 5 A.M., but the copy to a tape was still being triggered at 4 A.M. by the system administrator. As a result, all backups to a tape were unusable.
Know your recovery process in detail: If you test your backups, you will have the knowledge to answer questions regarding how long a full recovery will take. Answering that your full recovery will take around three and a half hours, but you prefer to say five hours just in case of any unexpected problem that you will come across, you will look more professional. This will let me know that you really know what you are talking about.
Document and improve your recovery process: The complete process needs to be documented. If the process is documented and you also allow your team to practice on a rotation basis, this will ensure that they are familiar with the course of action and will have all the knowledge necessary to know what to do in case of a disaster. You will now be able to rest in your home at night without being disturbed, because now you are not the only person in the team with the experience required to perform this important task.

Good for you if you have a solid backup and recovery plan in place. But have you tested that plan? Have you verified your ability to recover?

Protecting data

As being the main person responsible for the recovery and availability of the data, you need to have a full understanding of how to protect your data against all possible situations you could come across in your daily job. The most common situations you could see are:

Media failure
Hardware failure
Human error
Application error

Let's take a closer look at each of these situations.

Media failure

Media failure occurs when a system is unable to write or read from a physical storage device such a disk or a tape due to a defect on the recording surface. This kind of failure can be easily overcome by ensuring that your data is saved on more than one disk (mirrored) using a solution such as RAID (Redundant Array of Independent Disks) or ASM (Automatic Storage Management). In the case of tapes, ensure that your backups are saved in more than one tape and as mentioned earlier, testing the recoverability from them.

Hardware failure

Hardware failure is when a failure occurs on a physical component of your hardware such as when your server motherboard, CPU, or any other component stops working. To overcome this kind of situation, you will need to have a high availability solution in place as part of your disaster and recovery strategy. This could include solutions such as Oracle RAC, a standby database, or even replacement hardware on the premises. If you are using Oracle Standard Edition or Standard Edition One and need to implement a proper standby database solution, I will recommend you to take a closer look at the Dbvisit Standby solution for Oracle databases that is currently available in the market to allow you to fulfill this need (http://dbvisit.com).

Human error

Human error, also known as user error, is when a user interacting directly or through an application causes damage to the data stored in the database or to the database itself. The most frequent examples of human error involve changing or deleting data and even files by mistake. It is likely that this kind of error is the greatest single cause of database downtime in a company.

No one is immune to user error. Even an experienced DBA or system administrator can delete a redo log file that has the extension .log as a mistake when taking it as a simple log file to be deleted to release space. Fortunately, user error can most of the time be solved by using physical backups, logical backups, and even Oracle Flashback technology.

Application error

An application error happens when a software malfunction causes data corruption in the logical or physical levels. A bug in the code can easily damage data or even corrupt a data block. This kind of problem can be solved using Oracle block media recovery, and is why it is so important to have a proper test done prior to promoting an application change to any production environment.

Tip

Always do a backup before and after a change is implemented in a production environment. A before backup will allow you to roll back to the previous state in case something goes wrong. An after backup will protect you to avoid to redo the change in case of a failure, due that it was not included in the previous backup available.

Types of backup

Now that you understand all types of possible failures that could affect your database, let's take a closer look at the definition of backup and the types of backups that are available to ensure the recoverability of our data.

A backup is a real and consistent copy of data from a database that could be used to reconstruct the data after an incident. Consequently, there are two different types of backups available, which are:

Physical backups
Logical backups

A physical backup

A physical backup is a copy of all the physical database files that are required to perform the recovery of a database. These include datafiles, control files, parameter files, and archived redo log files. As an Oracle DBA, we have different options to make a physical backup of our database. Backups can be taken using user-managed backup techniques or using Recovery Manager (RMAN). Both techniques will be discussed in more detail later in this book. Physical backups are the foundation of any serious backup and recovery strategy.

A logical backup

Oracle uses Oracle Data Pump to allow us to generate a logical backup that can be used to migrate data or even do a partial or full recovery of our database. The utilities available are the Data Pump Export program (expdp) and the Data Pump Import program (impdp).

Many people have a misconception of these tools in thinking that they can only be used to move data. Data Pump is a very flexible and powerful tool that if well utilized can easily become a DBA's best friend. It is not just for moving data. It can also play a crucial role in your backup and recovery strategy.

Chapter 9, Understanding Data Pump and Chapter 10, Advanced Data Pump will go into more detail about the use of Data Pump for logical backup and recovery.

Note

The old Import and Export utilities

In the previous versions of Oracle we used to work with similar utilities called exp and imp. The exp utility is deprecated since Oracle 11g, but the imp utility is still currently supported by Oracle. The imp utility allows us to recover any backup generated by the old exp program. Just keep in mind that the use of exp is not supported anymore by Oracle and using it can bring future trouble to your environment.

Backup strategies

A backup and recovery strategy has the main purpose of protecting a database against data loss, and this document will contain all steps required to reconstruct the database after a disaster strikes. As the person responsible for the data of your company, it is very important to have a correct backup strategy in place to allow you to recover from any possible disaster.

Before you create a strategy, you will need to understand clearly all the Service Level Agreements (SLAs) in place with in your organization regarding this topic. To that end, you will need to ask some simple questions to the owners of the data:

How much data can the company lose in case of a disaster? (RPO)
How much time could the business wait to have the data restored and available again? (RTO)
How much will it cost the company for the loss of one hour of data?
What retention periods are required by law for the company data?

After receiving the answers to all these questions, you will be able to implement a proper backup and recovery strategy according to your real company needs and SLAs in place.

For example, if your company can only afford to lose three hours of data (RPO) but it can have the database down for up to 24 hours for a recovery process (RTO), all you will need to do to fulfill your SLA is to have a full backup of your database made daily. You will also need to make backups of all your archive logs every three hours to a tape or another network location to allow you to have all your data protected.

As part of creating a strategy, it is important to properly understand the concepts known as Recovery Point Objective (RPO) and Recovery Time Objective (RTO). As you can see in the following figure, the RPO reflects how much data might be lost without incurring a significant risk or loss to the business, and the RTO is basically the maximum amount of time allowed to reestablish the service after an incident without affecting the company seriously.

Key benefits

A practical reference to all Oracle backup and recovery options available, making it essential to any DBA in the world

A valuable guide for readers on the most frequent backup and recovery scenarios they can find in real life

Provides hands-on examples and a full hands-on lab to practise everything learned in this book

Description

The three main responsibilities of a successful DBA are to ensure the availability, recoverability, and performance of any database. To ensure the recoverability of any database, a DBA needs to have a strong backup and recovery skills set. Every DBA is always looking for a reference book that will help them to solve any possible backup and recovery situation that they can come across in their professional life. Oracle Database 12c Backup and Recovery Survival Guide has the unique advantage to be a reference to all Oracle backup and recovery options available, making it essential for any DBA in the world. If you are new to Oracle Database, this book will introduce you to the fantastic world of backup and recovery that is vital to your success. If you are an experienced DBA, this book will become a reference guide and will also help you to learn some possible new skills, or give you some new ideas you were never aware about. It will also help you to easily find the solution to some of the most well known problems you could find during your career as a DBA. This book contains useful screenshots, scripts, and examples that you will find more than useful. Most of the books currently available in the market concentrate only on the RMAN utility to backup and recovery. This book will be an exception to the rule and will become a must-have reference, allowing you to design a real and complete backup and recovery strategy. It covers the most important topics on Oracle database such as backup strategies, Nologging operations, new features in 12c, user managed backups and recoveries, RMAN (including reporting, catalog management, troubleshooting, and performance tuning), advanced data pump, Oracle Enterprise Manager 12c and SQL Developer. "Oracle Database 12c Backup and Recovery Survival Guide" contains everything a DBA needs to know to keep data safe and recoverable, using real-life scenarios.

Who is this book for?

This book is designed for Oracle DBAs and system administrators. The reader will have a basic working experience of administering Oracle databases. This book is designed for Oracle DBAs and system administrators.This book will become a reference guide and will also help you to learn some new skills, and give you some new ideas you never knew about, helping you to easily find the solution to some of the most well-known problems you could encounter as DBAs.

What you will learn

Understand all the options available for the backup and recovery of a database to be used in case of a disaster and how to survive it

Learn how to use RMAN and take advantage of its advanced functionalities

Use Data Pump for more than just backups, learning how powerful this utility is

Take advantage of Nologging operations in a safe and proper way

Perform backups and recovery properly in Multitenant and non-CDB environments

Take advantage of OEM12c and SQL Developer to fulfil your backup requirements and reduce risk in your organization

Understand the new features in 12c offered for backup and recovery and how to perform backup and recovery operations on it

Get familiar with the available range of Oracle products for backup and recovery, not only RMAN

What do you get with Print?

Instant access to your digital copy whilst your Print order is Shipped

Paperback book shipped to your preferred address

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Access this title in our online reader with advanced features

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Earl D. Shaffer Feb 15, 2014

Oracle Database 12c Backup and Recovery Survival GuidePACKT PublisherFrancisco Munoz AlvarezAman SharmaThis book should be part of every DBA's library. It covers the topics you would expect to be covered, but it does so in a conversational, yet professional, style. Especially as 12c becomes the 'next version to upgrade to' in 2014.After covering basic but important topics like archive/no-archive, restore vs recovery, effects of NOLOGGING, it covers RMAN vs Data Pump, cold vs hot backups, and provides scripts to help all this be clear.After covering RMAN in-depth, FRA, and V$ views, it cover real scenarios and shows how it all fits together in the real world.Buy the book today!

Amazon Verified review

Kai Yu Oct 03, 2013

It is great to see this new Oracle 12c database backup and recovery book. It has a comprehensive coverage of rman database backup and recovery techniques and experiences, and many different database backup and recovery scenarios in which DBAs can use a reference book for their daily database administration jobs, it also covers some latest 12c new features such as contrainer database (CDB) and pluggable database (PDBs) and how to backup and recovery the CDB and PDBs. I would say this is the great reference book for every DBA to have

Tushar Kanti Nath Jan 26, 2014

"Oracle Database 12c Backup and Recovery Survival Guide" book is very well written. Each chapter explains the backup and recovery concepts followed by examples and notes from authors to make the book unique and interesting to read. No doubt the contents of books reflect authors vast experiences in backup and recovery. I enjoyed reading this book which includes basics of backup recovery, what is new in 12c,RMAN troubleshooting and Tuning etc. and stongly recommend all oracle professional to read this book to uplift the backup and recovery skill sets.

jpo Nov 23, 2015

A dba can never have too much information. Especially about backup and recovery.

Marcus Vinicius M Pedro Aug 01, 2014

Oracle Database 12c Backup and Recovery Survival Guide is absolutely the most complete reference book to Oracle Database Administrators to learn how to maintain the databases recoverable.In this book, we have a comprehensive coverage of RMAN, the main tool for backup and recovery in Oracle Databases and the authors also covered different cenarios in which DBA's can live in the real life. It's definitely a book that can be used as a reference to use best practices in backup and recovery situations.It's also a great book because cover the new features for Oracle Database 12c, like CDB and PDB.If you wanna learn everything about backup and recover Oracle Database, you need to read this book!

Oracle Database 12c Backup and Recovery Survival Guide: A comprehensive guide for every DBA to learn recovery and backup solutions

What do you get with Print?

Oracle Database 12c Backup and Recovery Survival Guide

Chapter 1. Understanding the Basics of Backup and Recovery

Purpose of backup and recovery

Testing backups

Protecting data

Media failure

Hardware failure

Human error

Application error

Tip

Types of backup

A physical backup

A logical backup

Note

Backup strategies

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