Database corruption and inaccessibility of MDF files are serious issues faced by SQL administrators. Such corruption errors can affect business operations and even lead to revenue loss and reputation damage. Thus, it becomes crucial to resolving these errors to save your data.

In this article, we will discuss the reasons behind SQL database corruption and how you can resolve these errors with common ways to repair MDF files.

Reasons for SQL corruption

MDF files of SQL database are prone to many corruption errors. And there can be many reasons for the corruption of MDF files, such as hardware faults, issues with disks, subsystems, drivers, controllers, CPU, or memory module. Some of the major reasons behind the MDF file errors are:

  • If the SQL database is stored in a compressed folder, chances are it will get corrupt
  • Corruption in the hard drive where the MDF files are stored
  • If there is a network failure while using the SQL database, which could lead to corruption
  • Any modification or changes made in the SQL Server account
  • If the data is deleted accidentally from SQL Server
  • The disk drivers are defected or not updated
  • Due to corruption errors in the file header

When the MDF file becomes corrupt, it makes the SQL database inaccessible.

Besides, users also face a variety of error messages when the MDF gets corrupt.

Some of the common error messages displayed when the MDF files are corrupt include:

  • Metadata corruption error
  • A user may have deleted some data accidentally
  • Error message 823 in SQL Server/Error message 824 in SQL Server/Error message 825, etc.

These errors need to be resolved as soon as possible; else it could lead to major corruption errors.

Repairing damaged MDF files

It is quiet easy to repair the damaged MDF files. You can either chose to restore the MDF files from the last backup that your system had carried out or chose to execute the inbuilt DBCC CHECKDB command. Though it is easy to restore data from backup, backups may not be up-to-date always. So, it is always recommended to fix the corruption issues using DBCC CHECKDB command. And if the repair process is not a complete success, one can rely on professional MDF recovery tools too. We will discuss both the methods here.

Repair using the DBCC CHECKDB Command

DBCC commands or Database Console Commands (in Transact-SQL) help to check the physical and logical consistency of a Microsoft SQL Server database, and also to fix existing issues. The DBCC CHECKDB command performs functions of three commands, namely DBCC CHECKALLOC, DBCC CHECKCATALOG and DBCC CHECKTABLE, thus avoiding the need to run these commands one by one.

The DBCC CHECKALLOC command is used to check disk space allocation structures for a database, and the DBCC CHECKTABLE to check the integrity of the pages and the structures that build indexed view or tables; the third of these DBCC CHECKCATALOG is used to check the consistency of an online database. The DBCC CHECKDB thus helps in fixing all SQL database consistency issues. For this, run the command in following syntax:

[ ( database_name | database_id | 0
) ]
[ , MAXDOP = number_of_processors ]

How to repair MDF files more easily?

If the above method is not pretty helpful in resolving the errors or repairing the corrupt MDF files, then you should opt for an automated solution that can repair SQL database files quickly.

Kernel for SQL Database Recovery a simple alternative to the manual solution for repairing MDF/NDF files. It can quickly recover every object of an MDF/NDF file. Also, it offers a smooth working process, which makes it easier for every user to use the tool. To know better, look at the working process of this tool:

  • STEP 1: On launching the tool, a welcome window will appear on your screen. Browse and select the SQL database file that you want to repair. Click “Recover.” Select the SQL database file Note: If you know the SQL database version, then check that checkbox, otherwise, check the checkbox “Auto detect database version.”
  • STEP 2: The process will take a few seconds, and once it is done, you’ll be able to see the recovered data on the left pane of the tool. See the recovered data on the left pane
  • STEP 3: Click on any specific object on the left pane to preview its data before saving it. Preview its data before saving it
  • STEP 4: Now, to save data, select the required objects and click on the “Save” button in the upper left corner of the tool. A new saving window will open on your screen displaying the “Saving Mode.” Fill the required fields and click “OK.” select the required objects and click on the Save
  • STEP 5: The saving process will take some time. Once it is complete, a notification window will appear on the screen displaying “Saving done successfully.” Click “OK” to complete the process. Saving done successfully

This way you can easily recover the corrupt MDF/NDF files without going through the hassles of the manual method.


Repairing MDF files is very crucial to protect your SQL database, but when the corruption is severe, it becomes a little complicated to resolve the error with manual approaches. In this article, we not only mentioned the reasons behind the MDF corruption but also talked about the best solutions that can be used to repair the MDF files.