Wednesday, November 25, 2009

How to Resolve “Extent E_ID in database ID...” Error Message

The structure of an Index Allocation Map (IAM) page in MS SQL Server consists of one bit per dedicated extent for all the “Extents” in the file interval. The bit is allocated to the index of which the IAM page is a part. Corruption in the bit can result into inaccessibility of records stored in your database. Few major causes of corruption of the application damage, metadata structure corruption, malicious software like virus, and human errors. To access your data in such situations, restoration from an updated and valid database backup always helps. However, if the restoration could not be performed due to backup corruption, then the only way to access your data is by using advanced third-party SQL Server Recovery application.

Consider a practical scenario, where the underneath error message appears when you attempt to mount your SQL database:

“Extent E_ID in database ID DB_ID is allocated to more than one allocation object.”

The above error message halts the database mounting process making all the records saved in it inaccessible.


The fundamental reason responsible for the occurrence of the above error message is bit corruption that results in the allocation of same extent to two different IAM pages.

Note: The above error message can also occur due to physical damage of your system's component.


To resolve the above error message and to access the database records, take the below measures:

In logical crash circumstances, run DBCC CHECKDB command (with appropriate repair clause).
The physical damages can only be resolved by making the swapping the damaged component with the new component.

While the above resolution for physical damage is always successful, the DBCC CHECKDB does not provides complete surety of repairing database after all logical crashes. To permanently resolve all logical corruption scenarios, you will need to use advanced SQL Repair tools. Such SQL Database Repair applications are built by highly talented database recovery experts and use high end repairing methods to repair your database. These tools come with interactive user documentation, that makes them easy to understand without any prior technical understanding.

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