Week 9 – Chapter 8
- Methods to Backup Databases
- Types of data to be backed up
- Recovery models
- Recovery methods
Methods to Back up Data
• Maintenance Wizard (Chapter 7) to create
maintenance plan with scheduled backups
• Enterprise Manager to schedule job to
perform backup or to perform unscheduled
backup as required
• T-SQL commands
• Specialized packages such as Backup Exec
or Arcserv (not discussed here)
Prevent Loss of Data
Have a strategy:
1. To minimize data loss (malicious use of
delete, update statement, viruses, natural
disaster, theft)
2. To recover lost data
3. To restore data with minimal cost and
impact
Backup regularly:
1. Backup frequently if your database is OLTP
2. Backup less frequently if your database is
OLAP
Database Recovery Models
Set Database Recovery Model:
• Full Recovery Model
• Bulk logged recovery model
• Simple Recovery Model
Modify a database recovery model
1. Alter database pubs
2. Set recovery to bulk_logged
Backups
• SQL Server allows backups to occur while
users continue to work with the database
• Backs up original files and records their
locations
• Captures in the backup all database activities
that occur during the backup process
Backups (ctd)
Who can perform backup?
1. Members of the sysadmin fixed server role
2. Members of the db_owner and
db_backupoperators fixed database roles
Where to store backup?
1. Hard disk file
2. Tape
3. A location identified by a Named Pipe (3rd
party software package)
When to backup System Databases
• After modifying the master database:
• Using CREATE DATABASE, ALTER
DATABASE or DROP statement
• Executing certain Stored Procedures
• After modifying the msdb database
• After modifying the model database
When to backup User Databases
•
•
•
•
After creating a database
After creating an index
After creating a transaction
After performing un-logged operations:
• BACKUP WITH TRUNCATE_ONLY
OR NO_LOG OPERATIONS
• SELECT INTO statement
Restricted Activities during backup
•
•
•
•
•
Creating or modifying database
Performing autogrow operations
Creating indexes
Performing non-logged options
Shrinking a database
Create a Backup device
• A backup file that is created before it is
used for a backup is called a backup
device
• Why create permanent backup devices?
• To reuse backup files for future
backups
• To automate the backup
Create a Backup device(ctd)
Use sp_addumpdevice system procedure:
• Specify a logical name
• Logical and physical Names are stored in the
sysdevices system table
Example:
Use master
Exec sp_addumpdevice ‘disk’ ,
‘mybackupfile’,
‘c:\Backup|mybackupfile.bak’
Perform Backup without backup device
Why create backup without backup device?
• To perform one time backup
• To test backup operation that you plan to
automate
How to use backup database statement:
• Specify the media type (disk, tape, or
Named Pipe)
• Specify the complete path and full Name
Example:
Use master
Backup database Northwind
To Disk = ‘c:\temp\mycustomers.bak’
Types of Backup Methods
•
•
•
•
Full database backup
Differential backup
Transaction log backup
File or File group backup
Full Database Backup
• Provides a baseline
• Backs up original files, objects and data
• Backs up portions of the transaction log
Example:
Use master
Exec sp_addumpdevice ‘disk’, ‘NwindBac’ ,
‘D:\mybackupdir\Nwindbac.bak’
Backup database Northwind to NwindBac
Full Database Backup Options
WITH INIT: overwrites any previous backup on
that file
WITH NOINIT : appends the full database
backup to the backup file. Any previous
backup left intact.
Differential database backup
• Use on frequently modified databases
• Requires a full database backup before
• Backs up database changes since the last full
database backup
• Saves time in both backup and restore
processes
Example:
Backup Database Northwind
Disk = ‘D:\Mydata|Mydiffbackup.bak’
WITH DIFFERNTIAL
Transaction log backup
• Requires a Full database backup
• Backs up all database changes from the last
BACKUP LOG statement to the end of the
current Transaction log.
• Truncates the transaction log
Example:
Use master
Exec sp_addumpdevice ‘disk’,
‘Nwindbaclog’,
‘D:\Baclup\Nwind backuplog.bak’
Backup log Northwind To NwindBaclog
Backup using No-truncate Option
No-truncate option:
• Saves the entire Transaction log even if the
database is inaccessible
• Doesn’t purge the Transaction log of
committed Transactions
• Allows data to be recovered up to time of
system failure
Clear the Transaction log
• Use Backup statement to clear transaction
log
• Use truncate only or no_log option
• Can’t recover changes
• Is not recorded changes
Database file or filegroup backup
1. Use on very large databases
2. Backup the database files individually
3. Ensure that all database files in File group
are backed up
4. Back up transaction log
Example:
Backup database phoneorders
File = Orders2 To
orderbackup2
Backup log phoneOrders to orderlog