A DBCC CHECKDB failure error message (severity level 16 or 10) appears when corruption in database is beyond the repair limits of the command. Such severe corruption MS SQL Server database is caused due to metadata structure corruption, hardware damage, application damage, and improper server shutdown. Since, the inbuilt repair command is unable to repair the corrupted database, the database remains unmountable and its records also remain inaccessible. To access the database records in such cases, the user needs to restore the database from an updated backup. However, in case of incomplete database backup, the user can use a third-party MDF Repair utility to repair the database.

To illustrate the above situation in detail, consider the below error message that appears when you run DBCC CHECKDB command to repair corrupted database:

“DBCC results for 'FVD_A'. Msg 2511, Level 16, State 1, Line 1...

Table corruption in MS SQL Server database can occur during opening, closing, or modifying of the table. In most situations of database table corruption, users encounter an error message, which stops them from accessing the information saved in the table. The table can be corrupted either due to logical or physical factors. To access the information saved in the SQL Server table post its corruption, the user can restore the table from an updated backup. However, if the user has not created any backup or backup contains deficient values of the table, the user can repair the table using inbuilt repair command DBCC CHECKDB. The command, although successful in repairing table in most cases, can also result in loss of data from the table. To avoid any data loss, the user should opt for an effective third-party MDF Recovery application.

To explain the table corruption issue in detail, consider the below error message:...

You may come across SQL Server database corruption if the registry checkpoint of SQL Server agent is missing. In this case, SQL Server Agent cannot be found and MS SQL Server cannot start up. In such situations, MDF (Master Database File) of SQL Server becomes inaccessible and you come across critical data loss situations. To work around this problem, MDF Database Recovery is essential, if you do not have an updated backup.

As a practical example of this problem, consider this scenario:

The Registry checkpoint of SQL Server Agent is missing due to some unexpected deletion or unexpected corruption problems in the clustered instance of MS SQL Server 2008.

Clustered instance of Microsoft SQL Server 2008 is repaired.

In the above scenario, you cannot find the registry subkey, which is associated with the SQL Server Agent, in list of the checkpoints of SQL Server Network Name resource. SQL Server Network Name is associated with clustered instance. Furthermore, updates of SQL Server Agent application configuration aren't spread to other cluster nodes when SQL Server resource group goes to the nodes...

A particular set of resources, which have dependencies on several other resources is created, when you set up MS SQL Server on any cluster. You should not ever alter the default resources dependency tree. It may lead to several consistency and integrity issues in Microsoft SQL Server database. It may also lead to serious database corruption problems and need MDF Recovery to work around the issue.

Microsoft SQL Server Agent and Microsoft SQL Server shouldn't depend on a resource, other than specified resources. You are recommended not to make other database resources dependent upon MS SQL Server Agent or MS SQL Server. If it is essential to have dependency, you must play safely and follow the guidelines, recommended by Microsoft. The default resource dependency tree of MS SQL Server has the below implications:

The MS SQL Server Agent resources depend upon SQL Server resources...

A heap or clustered index in SQL Server is a way to effectively organize records saved in tables. These metadata structures enable the database user to increase retrieval speed of database records. While the heap index contains only the data pages, clustered index contains both index pages and data pages. Corruption in either of these indexes results in inaccessibility of all the database records. Few main reasons for index corruption are unexpected SQL Server shutdown, operating system malfunction, and virus attack. An easy way to surmount the problems created after index corruption is to restore the database from an updated backup. However, in case of database backup unavailability or backup falling short to restore the required data, the user needs to opt for an advanced third-party MDF Recovery application.

Consider a practical scenario, where you receive the below error message when your try to mount your database:...