Table error: object ID %d, index ID %d, partition ID %I64d, alloc unit ID %I64d (type %.*ls) B-tree level mismatch, page %S_PGID. Level %d does not match level %d from the previous %S_PGID.

Details
Product: SQL Server
Event ID: 2531
Source: MSSQLServer
Version: 9.00.1281.60
Symbolic Name: DBCC_BTREE_SIBLING_LEVEL_MISMATCH
Message: Table error: object ID %d, index ID %d, partition ID %I64d, alloc unit ID %I64d (type %.*ls) B-tree level mismatch, page %S_PGID. Level %d does not match level %d from the previous %S_PGID.
   
Explanation

There are two pages linked as immediate neighbors on a level of a B-tree. The level, LEVEL2, on the right page, P_ID2, does not match the level, LEVEL1, on the left page, P_ID1.

To determine which page is incorrect, examine the surrounding pages and the contents of the two pages in question. Also, look for MSSQLEngine_8931 errors that indicate B-tree parent-child level mismatches.

Possible Causes

This error can be caused by one of the following problems:

  • A random page corruption.

  • A bug in the B-tree manager.

  • If LEVEL1 and LEVEL2 are 0 or 1 and the index is a clustered index, there might be a bug in the Access Methods code that determines page levels. In ssVersion2005, for a clustered index, page levels progress from 0, 1, 2 to X; but in ssVersion2000, for a clustered index, page levels progress from 0, 0, 1, 2 to X; where X is the maximum depth of the B-tree.

A similar bug in the DBCC code that determines page levels.

   
User Action

Run hardware diagnostics and correct any problems. Also examine the Microsoft Windows system and application logs and the SQL Server error log to see whether the error occurred as the result of hardware failure. Fix any hardware-related problems that are contained in the logs.

If you have persistent data corruption problems, try to swap out different hardware components to isolate the problem. Check to make sure that the system does not have write-caching enabled on the disk controller. If you suspect write-caching to be the problem, contact your hardware vendor.

Finally, you might find it useful to switch to a new hardware system. This switch may include reformatting the disk drives and reinstalling the operating system.

Results of Running REPAIR Options

REPAIR will rebuild the index.

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