How to repair a corrupted SQL database (IAM multi-page error 8947)

SQL Server File Global Mapping (GAM) Page: An MS SQL Server file consists of several pages, which store their allocation structures. One of those pages is the Global Allocation Page (GAM). Contains the information related to the extensions assigned in that SQL Server file.

Index Allocation Map (IAM) Pages: Index Mapping Map (IAM) pages are the mapping pages that contain information about the extents that an index/table uses.

SQL table corruption due to multi-page IAM failure: Sometimes you encounter many errors due to multiple IAM pages for a single object. Such types of errors indicate table corruption. The error you may encounter after such table corruption of your SQL Server database states:

Server: Msg 8947, Level 16, State 1

Table Error: Multiple IAM pages for object ID O_ID, index ID I_ID contain mappings for the same range. IAM pages P_ID1 and P_ID2.

Why such an error could occur? If you encounter the error mentioned above, it means that the IAM chain for the specified index has at least 2 IAM pages (P_ID1 and P_ID) that cover the same GAM range (range is the file space used by the GAM page to map). is about 4 GB). Each index, which is allocated from a GAM range that has more than one extent, requires an IAM page for that specific GAM range. For all GAM interval extensions, an IAM page contains one bit for each extension. A set bit shows that the particular index is given to that index. A common reason for the IAM multi-page error that you may encounter can be a hardware failure. SQL database recovery becomes necessary for you in this case.

How to repair a damaged MDF file? You can perform the following methods for SQL database recovery:

• Replace damaged hardware – First of all, you should check if there are any issues related to hardware failure. For this, you can run hardware diagnostics and check your application, Windows error log, and SQL Server. If such a problem exists, replace the damaged hardware (if necessary).

• SQL database recovery from backup – If you have a clean backup for your SQL database, you can easily restore it. But, if there is no valid backup, you can use a third-party tool.

SQL database recovery using a third-party tool: You can invest in a SQL MDF repair tool, which is an easy, efficient, safe and time-saving way to fix the problem. One of these powerful SQL database recovery tools is SysTools SQL Recovery software. It is a superior tool with a user-friendly interface and employs advanced technology for efficient recovery and fast algorithms for quick MDF repair.