Have you ever encountered a situation where restoring a database from a backup took an unexpectedly long time? Or have you ever canceled a restore operation only to find that the database was successfully restored despite the error message?

In this blog post, we will explore the concept of backup and restore history in SQL Server and discuss a trace flag that can help in certain scenarios.

Recently, I had an interesting engagement with a client who was facing issues while restoring a database from a backup. Even though it was a small database, the restore operation was taking an unusually long time. When they canceled the operation, they received an error message indicating a problem with the msdb database.

Upon investigation, I discovered that the restore operation was indeed successful despite the error message. The issue was related to the logging of restore history in the msdb database. To simulate this issue in my lab, I took a lock on the restorehistory table in the msdb database.

When I attempted to restore a database while the lock was in place, I encountered a similar error message. However, upon checking the database, I found that it had been successfully restored. This confirmed that the logging of restore history in the msdb database was the cause of the error.

So, what can be done in such situations? If you are not concerned about the history of logging messages in the msdb database, you can use an undocumented trace flag called 3001. Enabling this trace flag prevents the logging of restore history in the msdb tables.

By using trace flag 3001, I was able to complete the restore operation without any errors, even though the blocking issue persisted. It is important to note that trace flags should be used with caution and only when necessary.

Trace flags are a powerful tool in SQL Server that can be used to modify the behavior of the database engine. They are typically used for troubleshooting or to enable certain features that are not available through regular configuration options.

While trace flags can be helpful in certain scenarios, it is important to understand their implications and limitations. They are undocumented features and may not be supported by Microsoft. Therefore, it is recommended to consult with a SQL Server expert or Microsoft support before enabling trace flags in a production environment.

In conclusion, understanding the backup and restore history in SQL Server is crucial for efficient database management. In some cases, issues with logging restore history can cause error messages, but the restore operation may still be successful. By using trace flag 3001, you can bypass the logging of restore history in the msdb database and complete the restore operation without errors.

Thank you for reading this blog post. I hope you found it informative and helpful. If you have any questions or would like to share your experiences with SQL Server backup and restore, please leave a comment below.