Applies to: SQL Server (all supported versions) Azure SQL Managed Instance
The msdb database is used by SQL Server Agent for scheduling alerts and jobs and by other features such as SQL Server Management Studio, Service Broker and Database Mail.
For example, SQL Server automatically maintains a complete online backup-and-restore history within tables in msdb. This information includes the name of the party that performed the backup, the time of the backup, and the devices or files where the backup is stored. SQL Server Management Studio uses this information to propose a plan for restoring a database and applying any transaction log backups. Backup events for all databases are recorded even if they were created with custom applications or third-party tools. For example, if you use a Microsoft Visual Basic application that calls SQL Server Management Objects (SMO) objects to perform backup operations, the event is logged in the msdb system tables, the Microsoft Windows application log, and the SQL Server error log. To help your protect the information that is stored in msdb, we recommend that you consider placing the msdb transaction log on fault tolerant storage.
By default, msdb uses the simple recovery model. If you use the backup and restore history tables, we recommend that you use the full recovery model for msdb. For more information, see Recovery Models (SQL Server). Notice that when SQL Server is installed or upgraded and whenever Setup.exe is used to rebuild the system databases, the recovery model of msdb is automatically set to simple.
- After any operation that updates msdb, such as backing up or restoring any database, we recommend that you back up msdb. For more information, see Back Up and Restore of System Databases (SQL Server).
- There are differences to whats available in the msdb database in Azure SQL Managed Instance. Review backup transparency to learn more.
Physical Properties of msdb
The following table lists the initial configuration values of the msdb data and log files. The sizes of these files may vary slightly for different editions of SQL Server Database Engine.
|File||Logical name||Physical name||File growth|
|Primary data||MSDBData||MSDBData.mdf||Autogrow by 10 percent until the disk is full.|
|Log||MSDBLog||MSDBLog.ldf||Autogrow by 10 percent to a maximum of 2 terabytes.|
To move the msdb database or log files, see Move System Databases.
The following table lists the default value for each database option in the msdb database and whether the option can be modified. To view the current settings for these options, use the sys.databases catalog view.
|Database option||Default value||Can be modified|
|Database Availability Options||ONLINE
|Service Broker Options||ENABLE_BROKER||Yes|
For a description of these database options, see ALTER DATABASE (Transact-SQL).
The following operations cannot be performed on the msdb database:
- Changing collation. The default collation is the server collation.
- Dropping the database.
- Dropping the guest user from the database.
- Enabling change data capture.
- Participating in database mirroring.
- Removing the primary filegroup, primary data file, or log file.
- Renaming the database or primary filegroup.
- Setting the database to OFFLINE.
- Setting the primary filegroup to READ_ONLY.
When you work with the msdb database, consider the following recommendations:
Always have a current backup of the msdb database available.
Back up the msdb database as soon as possible after the following operations:
- Creating, modifying, or deleting any jobs, alerts, proxies or maintenance plans
- Adding, changing or deleting database mail profiles
- Adding, modifying or deleting Policy based management policies
Do not create user objects in msdb. If you do, msdb must be backed up more frequently.
Treat the msdb database as highly sensitive and do not grant access to anyone without a proper need. Especially keep in mind, that SQL Server Agent jobs are often owned by members of the sysadmin-role and therefore make sure that code that is executed cannot be tampered with.
Audit any changes to objects in msdb
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