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1
Chapter Overview
• Understanding Data Restoration Issues
• Understanding the Types of Database Backups
• Understanding the Restoration Process
2
Data Restoration Goals
• Provide fault tolerance where possible.
• Monitor for problems before they occur.
• Plan for all forms of disasters.
• Determine acceptable data restoration times for each type of disaster.
• Quickly verify proper database functionality.
3
Types of Data Backups
Full database backup Differential database backup
Filegroup (or file) backup
Differential filegroup (or file) backup
Transaction log backup
Snapshot backup technology
4
Types of Data Restorations
Full database restore Filegroup (or file) restore with full recovery
Recovery to a point in time
Recovery to a named transaction
5
Databases to Back Up
• Applicable user databases
• The master system database
• The msdb system database
• The model system database, if this database has been customized
• The distribution system database, if replication is being used
6
Components of a Data Restoration Plan
• Document the entire system.
• Document the backup plan.
• Automate backups.
• Test the backup plan.
• Store backup media securely.
• Determine how long to retain backups.
7
Full Database Backups
• Complete copy of a database as of the end of the backup.
• Online backup with only a small impact on performance.
• Either a full database backup or a backup of all filegroups is the starting point for a database restoration.
• Perform after initial population of the database and periodically thereafter.
8
Differential Database Backups
• Complete copy of all database changes since the last full database backup
• Records only the most recent change
• Length of time required proportional to the number of modified extents
• Generally uses significantly less space than a full database backup
• Use with medium to large databases between full database backups
9
File and Filegroup Backups
F08vl01.FH8
10
Differential File and Filegroup Backups
• Complete copy of all changes in file or filegroup since the last full file or filegroup backup
• Conceptually the same as differential database backups
• Use to back up frequently changing tables in between full file or filegroup backups
11
Transaction Log Backups
• Sequential record of changes since the last transaction log backup.
• At the end of a transaction log backup, all VLFs containing inactive portions of the transaction log are truncated.
• Time and space required depends on frequency of changes to the database and frequency of transaction log backups.
• Frequency of transaction log backups depends on several factors.
12
Full Database Backup Strategy
13
Full Database and Transaction Log Backup Strategy
F08vl03.FH8
14
Differential Backup Strategy
15
Database File or Filegroup Backup Strategy
16
Automatic Recovery Process
17
Recovery Process Using a Full Database Backup
18
Recovery Process Using Filegroup (or File) Backups
19
Restoration and Recovery to Another Point in Time
20
Recovery Scenarios
• A user database data disk failure
• A user database transaction log disk failure
• A master database disk failure
21
Chapter Summary
• Develop, document, and test a data restoration strategy that anticipates all forms of disasters.
• Perform full database backups regularly, and use differential database backups between full backups to reduce recovery time.
• Perform frequent transaction log backups to provide redundancy and to truncate the transaction log.
• Use the Full Recovery model if point-in-time recovery or recovery to a specific mark is needed.