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...

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."...

Are you getting error messages repeatedly while working on a particular database in MS SQL Server 2000? If yes, then you should check the exact cause of these messages as there may be chances of database corruption. The database corruption can happen due to various reasons including virus infections, malfunctioning of the hardware components, abrupt or unplanned system shutdown while the database is open, etc, which could even make the database inaccessibile. In such cases, you should look for MDF file recovery using appropriate corrective methods, failing which you must use a third-party MS SQL Server recovery software to do the needful.

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

"Page P_ID in database ID DB_ID is allocated to both object ID O_ID1, index ID I_ID1, and object ID O_ID2, index ID I_ID2."

Cause:

The most prominent reason behind this error is that the index definitions in the IAM pages have damaged...

Are you using SQL Server 2008 in your organization to carry out enterprise solutions? If yes, then are you experiencing problems in using the database on a regular basis? If this is so, then there are chances that the database may have corrupted because of various reasons. Such reasons could be virus infections, power outages, abrupt system shutdown when the database is open, hardware malfunctioning, etc. In such cases, you should use appropriate corrective measures to repair SQL database. If you are not able to provide any solution, then you should use a third-party MS SQL repair software to do the needful.

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

“Table error: Object ID O_ID, index ID I_ID, partition ID PN_ID, alloc unit ID A_ID (type TYPE). The off-row data node at page P_ID1, slot S_ID1, text ID TEXT_ID is pointed to by page P_ID2, slot S_ID2 and by page P_ID3, slot P_ID3.”...

Microsoft SQL uses indexes to effectively manage the database and improve its performance. It helps database manager to easily locate the specified table and extract it. However, in some situations the indexes may get damaged due to high fragmentation and database may become inaccessible. To overcome such issues, SQL provides you a tool, called DBCC DBREINDEX, to rebuild the database indexes. But, sometimes, this tool fails to work and database remains in unusable state. This behavior leads to critical data loss situations and requires SQL database recovery to be fixed, if there is no updated backup in place.

In a practical situation, access violation may occur in CTableMetadata::LoadIndex function when you run the DBCC DBREINDEX on an SQL Server table that contains hypothetical indexes. Such indexes are created by Index Tuning Wizard during tuning process. They are generally dropped at the end of Index Tuning Wizard procedure. But, sometimes these indexes are not deleted correctly...

The system catalogs in SQL Server databases are used to store various types of information such as number and names of tables and views in the database among many others. This information is collectively referred as metadata. However, sometimes this metadata may get corrupt due to various reasons such as virus infections, hardware issues, power outages, etc. In such cases, you should use the in-place methods to rectify the problem. However, if you are not able to recover SQL database, then you should use a third-party Repair SQL database software to do the needful.

Consider a scenario wherein you encounter the following error message while using the DBCC CHECKNAME tool on an SQL Server 2008 database:

"Database 'DBNAME': consistency errors in system catalogs prevent further DBCC CHECKNAME processing."

Cause:

There could be the following causes for this error. They are:

The system base tables are storing the metadata for all the objects in the database...

As you store more and more data to your Microsoft SQL Server database, the size of database increases and the performance of Microsoft SQL Server decreases day by day. Large size of database may also cause system crash and sometimes database corruption. To prevent such situations, MS SQL Server provides SHRINKFILE and SHRINDB tools for reducing size of the database. However, in some cases, these tools fail to shrink the database and problem remains intact. At this point, if database corruption occurs, SQL database repair becomes need of hour.

As a practical example of this behavior, you may come across the following error message when you try to reduce size of the SQL Server 2000 database using SHRINKFILE, SHRINKDB, or SQL Server Enterprise Manager:

"2002-11-25 22:41:30.18 spid55 Time out occurred while waiting for buffer latch type 4,bp 0x3d03340, page 1:37939357), stat 0xb, object ID 8:8:0, EC 0xB39B55E0 : 0, waittime 300. Not continuing to wait...

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>'”...