How to Restore MS SQL Database from Corrupt Backup?

One of the major challenges that SQL Server admins face nowadays is corruption in MDF file. When a database is corrupted, it goes into the suspect state or you may fail to access the tables, stored procedures, or other objects in it. In such a situation where your database file gets corrupted, the easy solution is to restore it from a backup file. While restoring the backup file, you may encounter the restore failed errors like “The database cannot be recovered because the log was not restored,” “Database cannot be opened. It is in the middle of a restore,” “Error 3183: Corrupt SQL Backup File,” etc. Such errors often occur due to corruption in the backup file.

If the backup file is corrupted or damaged, there is no native method available in SQL Server to repair it. The only option left here is to take the help of a reliable recovery tool to restore SQL database. In this article, we’ll learn the causes of corruption in the backup file and how to restore the MS SQL database from the corrupt backup.

Causes of Corruption in the Backup File in SQL Server

Corruption in backup file can occur due to one of the following reasons:

Malware or virus infection in the system hosting the BAK file/server.
Bad sectors on the hard drive where the backup file is located.
Sudden restart of the MS SQL Server instance.
Sudden system shutdown while working on the backup database.
Bugs in MS SQL Server.

Method to Restore Database from Corrupt MS SQL Backup File

If your backup (.bak) file is corrupted due to any reason, then you need to repair it. SQL Server does not have any built-in method to repair or recover a corrupt backup file. To repair the corrupt BAK file, you can use MVPs-recommended SQL repair tool – Stellar Repair for MS SQL Technician.

This professional tool is specialized in restoring data from corrupted or damaged SQL Server database backup files of any size or in any state. It can recover all the data, including indexes, tables, triggers, and stored procedures, with absolute precision. Also, it can effectively recover data from files of Full, Differential, and Transaction log backups. After recovering, it allows you to save it to a new database, live database, or other formats, such as CSV, HTML, XLS, etc. Here are a few simple steps to repair and restore backup file using Stellar Repair for MS SQL Technician:

Download, install, and launch Stellar Repair for MS SQL Technician software.
On the software dashboard, you will see the following three tools:
Repair MS SQL Database
Recover MS SQL Password
Extract from MS SQL Backup

Click the Extract from MS SQL Backup option. A window will appear. From there, click on the Browse option to select the corrupt BAK file. Click Scan.

In Select Scan mode, select any one option: Standard Scan or Advanced Scan.

Next, click OK.
In Select Backup set, select a backup to recover, and then click Next.

Next, the repair process will begin. When you see the Repair Complete message, click OK.

The tool’s demo version displays a preview of the recovered records in the corrupt BAK file. To save the recovered file, you need to activate the tool. Then, click Save on File menu.
In the “Save Database” window , under the Saving option, select one of the following options as per your requirement:
New Database
Live Database
Other formats
And, click Next.
In the “Connect to Server” dialog box, select MS SQL as the server name, the Authentication method, and the destination location to save the repaired bak file. Click OK.

Once your corrupt backup file is repaired and saved, then you can extract the MDF file from it.

Read: Ransomware recovery – How Stellar restored SQL data from encrypted database.

Tips to Prevent Corruption in MS SQL Database File

You can follow the given measures to prevent corruption in the MDF/NDF file:

Take regular backups of your MS SQL database by choosing a consistent backup method according to your needs.
Power outage can interrupt MS SQL applications’ ongoing operation and result in corruption in database. So, ensure you have an uninterrupted power supply/UPS to avoid sudden power failure.
Keep an updated version of the antivirus program on your machine to prevent virus/malware attack.

Conclusion

If the SQL database restore process is failed, you can use the CONTINUE_AFTER_ERROR command to continue the restore process even if the file is corrupted. This workaround only works if the file is slightly corrupted. If the backup file is severely corrupted, you can use a SQL repair tool, like Stellar Repair for MS SQL Technician as mentioned in the post. This tool repairs corrupt backup files and database files as well. It can easily restore the objects from corrupt MDF/BAK file to a new file at the desired location, with complete integrity.