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Backup and Recovery in SQL Server. High Level View. Planning. Needs assessment Management expectations Network architecture Personnel. Implementation. Training Who’s involved in the process? Testing Failsafe your process Remember what the purpose of backups are!. The Role of Back-ups.
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Planning • Needs assessment • Management expectations • Network architecture • Personnel
Implementation • Training • Who’s involved in the process? • Testing • Failsafe your process • Remember what the purpose of backups are!
The Role of Back-ups • Data Recovery • Data Migration
Backup Basics • Data Files • .MDF • .LDF • Backup Devices • Create • Delete
Recovery Models • Simple • Most restrictive model. • Can’t complete transaction log backups. • Good if you only want to recover to your last full backup. • Bulked Log • Ability to recover to the end of a full backup or the end of a transaction log. • Lose the ability to restore to a specific point in time. • Full • Allows full, differential, transaction log and filegroup recoveries. • Provides the highest level of data protection. • Point in time restores.
Types of Backups • Full Database • Differential Database • Transaction Log • Filegroup
Full • Completes a full backup up the database right up to the point where the database finishes. • Backs up all tables, indexes, system tables and the database object in those tables • Striping example
The Backup Database Statement BACKUP DATABASE { database_name | @database_name_var } TO < backup_device > [ ,...n ] [ WITH [ BLOCKSIZE = { blocksize | @blocksize_variable } ] [ [ , ] DESCRIPTION = { 'text'| @text_variable } ] [ [ , ] DIFFERENTIAL ] [ [ , ] EXPIREDATE = { date | @date_var } | RETAINDAYS = { days | @days_var } ] [ [ , ] PASSWORD = { password | @password_variable } ] [ [ , ] FORMAT | NOFORMAT ] [ [ , ] { INIT | NOINIT } ] [ [ , ] MEDIADESCRIPTION = { 'text'| @text_variable } ] [ [ , ] MEDIANAME = { media_name | @media_name_variable } ] [ [ , ] MEDIAPASSWORD = { mediapassword | @mediapassword_variable } ] [ [ , ] NAME = { backup_set_name | @backup_set_name_var } ] [ [ , ] { NOSKIP | SKIP } ] [ [ , ] { NOREWIND | REWIND } ] [ [ , ] { NOUNLOAD | UNLOAD } ] [ [ , ] RESTART ] [ [ , ] STATS [ =percentage ] ]
Differential Backup • Creates a backup of the changes made to the database since the last full backup • Does not keep track of individual transactions so it does not provide the ability to restore to a point in time
The Transaction Log • The transaction log keeps a log of each transaction giving a DBA the ability roll forward or roll back to a specific point. • When the transaction log is backed up the log is truncated. • Transaction log backups are scheduled in intervals typically 5 to 30 minutes. • Backs up the transactions since the last Full Backup, Differential Backup or Transaction Log Backup.
Backup Log Statement BACKUP LOG { database_name | @database_name_var } { TO < backup_device > [ ,...n ] [ WITH [ BLOCKSIZE = { blocksize | @blocksize_variable } ] [ [ , ] DESCRIPTION = { 'text'| @text_variable } ] [ [ ,] EXPIREDATE = { date | @date_var } | RETAINDAYS = { days | @days_var } ] [ [ , ] PASSWORD = { password | @password_variable } ] [ [ , ] FORMAT | NOFORMAT ] [ [ , ] { INIT | NOINIT } ] [ [ , ] MEDIADESCRIPTION = { 'text'| @text_variable } ] [ [ , ] MEDIANAME = { media_name | @media_name_variable } ] [ [ , ] MEDIAPASSWORD = { mediapassword | @mediapassword_variable } ] [ [ , ] NAME = { backup_set_name | @backup_set_name_var } ] [ [ , ] NO_TRUNCATE ] [ [ , ] { NORECOVERY | STANDBY = undo_file_name } ] [ [ , ] { NOREWIND | REWIND } ] [ [ , ] { NOSKIP | SKIP } ] [ [ , ] { NOUNLOAD | UNLOAD } ] [ [ , ] RESTART ] [ [ , ] STATS [ =percentage ] ] ]
Filegroups • Allow a user to place tables, indexes and other database objects into specific database files. • Can be backed up and restored individually or in groups. • Useful when time restraints prevent full backups.
Verifying the Backup • Does not check the consistency of the database (i.e. DBCC CHECKDATABASE). • Verifies the integrity of the database backup and checks for corruption. • Makes sure all the data in the backup set is readable.
Restore Verify Only RESTORE VERIFYONLY FROM < backup_device > [ ,...n ] [ WITH [ FILE =file_number ] [ [ , ] { NOUNLOAD | UNLOAD } ] [ [ , ] LOADHISTORY ] [ [ , ] PASSWORD = { password | @password_variable } ] [ [ , ] MEDIAPASSWORD = { mediapassword | @mediapassword_variable } ] [ [ , ] { NOREWIND | REWIND } ]
Job Scheduling • The most widely used way complete day to day and week to week scheduled backup operations. • Creation of jobs though Enterprise Manager. • SQL Server Agent must be started.
Database Maintenance Plans • Expanded job scheduling abilities. • Creates jobs managed by the SQL Server Agent. • Can schedule integrity checks, reorganize indexes and delete unwanted database backups.
Storage • Using a consistent method of keeping track of your backups. • Using the system backup tables in the msdb database. • Archiving backups to tape and different considerations for different industries
Restore scenarios • Data Migration • Development • Testing • Disaster Recovery • Recovering Backups • Standby Servers
Restore Basics • Make sure you are using the correct backup set. • RESTORE LABELONLY: summarizes information about the backup set. • RESTORE HEADERONLY: returns information about each item in the backup set including the order in which the backups were made. • RESTORE FILELISTONLY: returns the associated data files in relation to a specific backup device.
Restoring a Full Backup and a Differential Backup • Restore a full backup. • Restoring a differential. • The WITH RECOVERY/NORECOVERY clause. • Files must be restored in order.
The Restore Statement RESTORE DATABASE { database_name | @database_name_var } [ FROM < backup_device > [ ,...n ] ] [ WITH [ RESTRICTED_USER ] [ [ , ] FILE = { file_number | @file_number } ] [ [ , ] PASSWORD = { password | @password_variable } ] [ [ , ] MEDIANAME = { media_name | @media_name_variable } ] [ [ , ] MEDIAPASSWORD = { mediapassword | @mediapassword_variable } ] [ [ , ] MOVE 'logical_file_name' TO 'operating_system_file_name' ] [ ,...n ] [ [ , ] KEEP_REPLICATION ] [ [ , ] { NORECOVERY | RECOVERY | STANDBY = undo_file_name } ] [ [ , ] { NOREWIND | REWIND } ] [ [ , ] { NOUNLOAD | UNLOAD } ] [ [ , ] REPLACE ] [ [ , ] RESTART ] [ [ , ] STATS [ =percentage ]
Restoring a Full Backup and Tlogs • Must restore files in order • Provides the ability to restore to a point in time • Provides the ability to restore to a marked transaction
Restore Log Statement RESTORE LOG { database_name | @database_name_var } [ FROM < backup_device > [ ,...n ] ] [ WITH [ RESTRICTED_USER ] [ [ , ] FILE = { file_number | @file_number } ] [ [ , ] PASSWORD = { password | @password_variable } ] [ [ , ] MOVE 'logical_file_name' TO 'operating_system_file_name' ] [ ,...n ] [ [ , ] MEDIANAME = { media_name | @media_name_variable } ] [ [ , ] MEDIAPASSWORD = { mediapassword | @mediapassword_variable } ] [ [ , ] KEEP_REPLICATION ] [ [ , ] { NORECOVERY | RECOVERY | STANDBY = undo_file_name } ] [ [ , ] { NOREWIND | REWIND } ] [ [ , ] { NOUNLOAD | UNLOAD } ] [ [ , ] RESTART ] [ [ , ] STATS [=percentage ] ] [ [ , ] STOPAT = { date_time | @date_time_var } | [ , ] STOPATMARK ='mark_name' [ AFTER datetime ] | [ , ] STOPBEFOREMARK ='mark_name' [ AFTER datetime ]
Point in Time Restore • Allows user to restore to a point before a failure or corrupt data • Allows user to restore without unwanted data
Restore to Mark • STOPATMARK: Transactions can be ‘marked’ so that a restore can take you up to that marked transaction. • STOPBEFOREMARK: Restores can also restore up to but not including that mark.
Using a Backup to Create a New Database • A new database can be created by using the backup from an existing database. • This is made possible by using the ‘with move’ statement which copies the data files and applies them to the new database.
Consistency in Backing Up the System Databases • It is important to consistently backup up the master database and the msdb databases. • In a restore scenario the master database should be restored first and the msdb database should be restore next followed by the model. • The user databases should be restored last.
Discussion • Disaster Recovery scenarios. • Added input from user experience. • Discussion/Comments