IT390 Business Database Administration Unit 5 : Backup and Restoring Tasks

©2006 ITT Educational Services Inc. Course Name: IT390 Business Database Administration Unit 5 Slide 1

IT390 Business Database AdministrationUnit 5 :Backup and Restoring Tasks


Objectives

• Backup, Recover and Replicate a Microsoft SQL Database Server.

• Implement database backup in SQL Server 2000.• Explain the importance of database restoration in SQL Server

2000.• Explain various database recovery models in SQL Server 2000.• Restore and rebuild a master database.• Explain the process and features of Replication.


SQL Server Backup

• SQL Server supports several types of backup: A complete backup makes a copy of the entire

database A differential backup makes a copy of the database

changes since the last complete backup Differential backups are faster and can be taken more

frequently Complete backups are simpler to use for recovery

• The transaction log also needs to be periodically backed up


Database Recovery

• Both data and log files are created by SQL Server• SQL Server provides a wizard for setting up database

maintenance plan, e.g., scheduling database and log backups

• To recover a database with SQL Server: The database is restored from a prior database

backup Log after images are applied to the restored database At the end of the log, changes from any transaction

that failed to commit are then rolled back


SQL Server Recovery Models

• Three recovery models Simple recovery: neither logging is done nor log

records applied:• To recover a database is to restore the database to the

last backup

• This method can be used for a database that is never changed

Full recovery: all database changes are logged Bulk-logged: all changes are logged except

those that cause large log entries


Julia, the DBA at Ralphsoft Inc., is assigned the responsibility of making backups of critical databases every Friday.

How can she perform this task?

Activity


• A backup of a database is another copy of the database stored in another physical location, which may be a disk or a tape.

• In SQL Server 2000, you can make the following backups:

Full backup Differential backup Transaction Log backup File Group backup

Backups


• List the tasks that need to done before performing a backup on a critical database.

Class Activity


• In SQL Server 2000, you can perform backups using:

Enterprise Manager

T-SQL

Backup Wizard

Performing Backups


• List the steps to perform backup using Enterprise Manager (Pages 7.7 – 7.19).

Class Activity


• You can perform a backup using T-SQL in the following manner:

EXEC sp_addumpdevice 'disk', 'master_backup',

'c:\Program Files\Microsoft SQL Server\MSSQL\BACKUP\ masterbackup.bak'

BACKUP DATABASE master TO master_backup WITH INIT

Performing Backup Using T-SQL


• What is the output of the following T-SQL statement?

EXEC sp_addumpdevice 'disk', 'Inventorylog', ‘C:\BACKUPS\inventory_backup.dat‘ BACKUP LOG inventory TO Inventorylog

Class Activity


• Write the command to create a backup for the Employee database named Employee_backup.

• The backup must be stored on a disk device named empbackup at the location, C:\Backups\empbackup.bak.

Class Activity (cont)


• List the steps to perform a backup using the Backup wizard.

Class Activity (cont)


• Recovery is a method provided by SQL Server 2000 to restore the database that you backed up.

• You can recover your data from any of the following types of failures:

Permanent loss of servers

Media failures

User errors

Recovery


• The following recovery models are available in SQL Server 2000:

Simple recovery Full recovery Bulk-logged

Recovery (cont)


• SQL Server provides the following options to restore a database:

Restore the database and its transaction log. Restore from a full database backup to a differential

backup. Restore from a file group backup.

Restoration


• What is achieved by the following T-SQL statement?

RESTORE DATABASE SALES FROM SALES_BACKUPRESTORE LOG saleslog FROM saleslog_backup WITH RECOVERY

Class Activity


• The master database stores various types of configuration information about SQL Server and all the user-defined databases.

• SQL Server provides a utility called rebuildm to rebuild the master database.

• You cannot rebuild the master database if you do not have its backup.

Restoring and Rebuilding the Master Database


• List the steps to rebuild and restore the master database in case of a failure.

Activity


• In a distributed DBMS environment, multiple copies of a database are maintained across geographical regions. Data is generally stored in a region or department where it is needed the most.

Distributed DBMS Architecture

Location A

Location B Location C


• Database replication is the process of making the copies of a database available to different database users spanning across different locations. Data is replicated for:

Data sharing Reduction in network traffic Database backup

Database Replication


• Different database replication models are used for making replicas of the main database. These models are:

Snapshot Transactional Merge

Database Replication (cont.)


• In the snapshot database replication model, the replica of the main database consists of an exact copy of the data and database objects present in the central database at any point in time.

Snapshot Database Replication Model

Location A


M ain D atabase

Local D atabase

Local D atabase

XXXX

YY YYXXY Y

XXXX

YY YYXXY Y

XXXX

YY YYXXY Y


Snapshot


• The transactional replication model is used in organizations where data needs to be replicated as soon as transactions take place or as data gets modified in the central database.

Transactional Database Replication Model

Location A


M ain D atabase

Local D atabase

Local D atabase

XXXYY YYXXY Y

XXXX

YYYYXXYY

XXX

XXX

XXXX

YYYYXXYY XXX

YY YYXXY Y


Transactional……….Changes only


• The merge database replication model is used by organizations in which local users can modify the local database copies without simultaneously updating the central database.

Merge Database Replication Model

M ain D atabase

M ain D atabase

XXXX

Y Y Y YXXY Y

XXX

YYYXXY

XXX

YYYXXY

XXX

YYYXXY

XXX

YYYXXY

XXXYYY

XXY


Continuous Merges may be inefficient


Summary

• Creating a Backup and Managing a restore with Transact SQL and Enterprise Manager is a key skill

• Database restoration is a key procedure in case of failure. A business cannot afford to lose their data

• There are several options for backing up and recovering databases.

• Replication is the maintenance of data at multiple sites. There are several methods to replicate data.


Did you understand the key points from the Lesson?

Do you have any questions?

Summary

IT390 Business Database Administration Unit 5 : Backup and Restoring Tasks

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