Microsoft SQL Server is a reliable and advanced database management system that provides you various database management and SQL database recovery algorithms. DBCC CHECKDB is one of the most advanced SQL Server commands that helps you repair corrupt database. However under some situations, this command fails with an error and cannot repair damaged database. This behavior leads to critical data loss and requires SQL Server recovery to be fixed.

DBCC CHECKDB command may not recover SQL Server database due to various reasons, such as metadata structure corruption, system table damage, and faulty database index. For instance, consider the following error message that occurs when you try to perform MS SQL recovery using DBCC CHECKDB command-

"Database MyDB: Check Data and Index Linkage...

Microsoft SQL-DMO (ODBC SQLState: 42000)] Error 8921: [Microsoft][ODBC SQL Server Driver][SQL Server]CHECKTABLE terminated. A failure was detected while collecting facts. Possibly tempdb out of space or a system table is corrupt. Check previous errors...

An IAM (Index Allocation Map) is a page in the database that stores one bit per extent in all the GAM (Global Index Map). A set bit is used to point out that the extent is allocated to that particular index. At times, this convention is not followed as two IAM pages refer to the same GAM interval. Lot of times, this problem is caused due to database corruption, which in turn, can occur because of virus infections, database header corruption, abrupt or unplanned system shutdown, etc. There are several methods that can be used to achieve MDF file recovery. However, if you fail to do so then you should use a third-party SQL recovery software to do the needful.

Let us assume a situation in which you are getting the following error message while working on the MS SQL Server 2000 database:

“Table error: Multiple IAM pages for object ID O_ID, index ID I_ID contain allocations for the same interval. IAM pages P_ID1 and P_ID2.”...

MS SQL Server database is build up of various metadata structure components like, pages, extent, etc. Pages are the smallest unit of data storage that store actual data. A combination of 8 adjacent pages makes an Extent. Corruption or damage in metadata structure primarily results in inaccessibility of records stored in your database. In most of the database corruption situation, you encounter an error message stating the cause for the error. For successful access of records stored in your database and overcoming hazards created by error message, an easy way is to restore the database records from an updated backup. But if in case, your backup file has been corrupted, damaged, or unreadable, then you will need to use advanced repair software that can comprehensively repair MDF files.

Consider a practical case, where you encounter the below error message when you attempt to access the records stored in your MS SQL Server database:

"Table error: Extent P_ID object ID O_ID, index ID I_ID is beyond the range of this database."...

Microsoft usually recommends you to use a SAN (Storage Area Network) or locally attached hard drives to store your MS SQL Server database (MDF or Master Database File) because it optimizes the reliability and performance of Microsoft SQL Server. Use of the network database files (the files stored on NAS [Network Attached Storage] or networked server) isn't enabled for MS SQL Server. However, this configuration may damage your SQL Server database in some cases of system failure. In such situations, you must have an absolute backup of your significant database to extract inaccessible data from it. In the other case, you need to go for master database file recovery solutions to get your valuable data back.

Although, network file support is not enabled by default in Microsoft SQL Server, you can manually configure MS SQL Server to store all your database files on NAS storage server or networked server. The servers, which you employ for this configuration, must fulfill MS SQL Server requirements for write-through guarantees and data write ordering...

The DBCC CHECKDB command in SQL Server databases is used to check and repair any inconsistency in the databases. There are many extensions for this command that you can apply in various kinds of situations. However, at times when you this command finds any error on the system tables then it ends abruptly. Such cases can arise due to corruption in the database tables. In such situations, you should employ certain in-built workarounds to get the database repaired. If you are not able to recover the database using these methods, then you should use a third-party SQL database recovery software to recover SQL database.

Consider a scenario wherein you encounter the following error message while working on an SQL Server 2008 database:

"System table pre-checks: Object ID O_ID. Page P_ID has unexpected page type PAGETYPE. Check statement terminated because of an irreparable error."

Cause:...

Like other databases and files, Microsoft SQL Server database may also come across various corruption issues. The corruption can take place due to various reasons, including the internal database or SQL Server application issues and system related problems. One major system related problem, which can cause MDF (Master Database File) corruption, is I/O logical check failure. In such situations, the database becomes totally inaccessible and you come across severe data loss situations. In order to get your mission critical data back, you need to repair and restore the corrupt database using SQL database recovery solutions.

The I/O logical check failure can be indicated by various error messages, which includes the following one:

“Error 823 I/O error <error> detected during <operation> at offset <offset> in file '<file>'”...

In Microsoft SQL Server, if any transaction violates the integrity constraints during execution, database inconsistency occurs. The transaction leaves your MS SQL Server database in illegal state and it gets aborted with an error. Database inconsistency leaves your MDF (Master Database File) in an unusable and inaccessible state, which can lead to serious data loss. In such cases, a valid and updated backup come for your rescue. You can easily restore all your valuable data from current backup and prevent needs of SQL recovery using third-party applications.

However, in case you are unable to restore data from the backup or backup is incomplete, you can check the database errors and fix them using inbuilt utility of Microsoft SQL Server, called CHECKDB. It offers you an option to repair the database errors. Database inconsistency may also occur due to system level errors, like file system and hardware. You are highly recommended to fix these errors before repairing the database, else you may face the same problem again after some time...

In SQL Server 2008, the Auditing feature has been introduced that allow you to track user and system activity for the enterprise customers. This feature provides the option to detect any unauthorized access attempts, if any, to the SQL Server database. Also, it facilitates a rich and powerful tracking capability to recognize any sensitive configuration changes to the database by the administrators. However, at times the auditing process can fail thereby making the database get corrupt. You should use appropriate corrective measures to rectify the problem. If you are not able to address the situation, then you should use a third-party SQL recovery tool software to recover SQL database.

Consider a scenario wherein you encounter the following error message while auditing a database table in SQL Server 2008.

“Table error: alloc unit ID A_ID, page P_ID. The test (TEST) failed. The values are VAL1 and VAL2.”

Cause:...