Monday, October 5, 2009

Applying CHECKDB On Tempdb Cause Data Loss

The tempdb database is a global resource of MS SQL Server, which is available for all users that are connected to instance of Microsoft SQL Server. This database stores temporary user objects, internal objects that are designed by SQL Server Database Engine, row versions that are resulted by data alteration transactions and row version that are resulted by data alteration transactions for features. In some cases, when you try to repair a damaged tempdb database using CHECKDB command, SQL Server database corruption may occur. This behavior renders all of your mission-critical data inaccessible and thus you need to opt for SQL Recovery solutions to retrieve data.

In a practical scenario, when any of the database user raise attentions during process of SQL Server, you might come across any of the below error message:

Server: Msg 8946, Level 16, State 1, Line 1
Table Corrupt: Allocation page (1:253) has invalid IAM_PAGE page header values. Type is 1. Check type, object ID and page ID on the page.

Or

Server: Msg 8906, Level 16, State 1, Line 1
Page (1:253) in database ID 2 is allocated in the SGAM (1:3) and PFS (1:1), but was not allocated in any IAM. PFS flags 'IAM_PG MIXED_EXT ALLOCATED 0_PCT_FULL'.

Attains are raised by SQL Server clients while server is executing or performing commands, necessitating non-logged allocations in tempdb file like worktables for the cursors.

Cause

As stated in above error, this issue is caused by corruption to the SQL Server database table. When the database table gets damaged, an invalid value is written in header of IAM_PAGE page of table and the operating system could not identify table and gives you error messages.

Corruption to the SQL Server database table might occur due a number of reasons ranging from improper system shutdown to virus infection. When database corruption occurs, it neither accessed nor repaired through CHECKDB utility.

In such situations, you need to repair and restore the database using third-party SQL Repair applications to retrieve inaccessible or damaged data. The SQL Recovery tool perform systematic scan of affected database to ensure absolute recovery.

The software are quite easy to use as they have self-descriptive and interactive graphical user interface. SQL Repair is completely safe with these programs as they have read-only and non-destructive conduct.

Stellar Phoenix SQL Recovery is the most effective and advanced software that can handle most of the SQL Server database corruption scenarios. It supports Microsoft SQL Server 2008, 2005 and 2000. The software is compatible with Microsoft Windows Vista, 2003, XP, 2000 and NT.

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