How to Fix a Corrupt SQL Database (Multiple IAM Pages Error 8947)
Global Allocation Page (GAM) of SQL Server File: An MS SQL Server file consists of various pages, which store its allocation structures. One such page is the Global Allocation Page (GAM). It contains the information that is related to the allocated extents in that SQL Server file.
Index Allocation Map (IAM) Pages: Index Allocation Map (IAM) pages are the allocation pages that contain information of the extent that an index/table uses.
SQL Table Corruption Due to Multiple IAM Pages Error: Sometimes, you may encounter errors due to multiple IAM pages for a single object. Such types of errors indicate table corruption. The error you might encounter after such corruption in your SQL Server database table states:
Server: Msg 8947, Level 16, State 1
Table error: Multiple IAM pages for object ID O_ID, index ID I_ID contain allocations for the same interval. IAM pages P_ID1 and P_ID2.
Why Might Such Error Occur? If you are encountering the aforementioned error, then it implies that the IAM chain for the specified index has at least 2 IAM pages (P_ID1 & P_ID) covering the same GAM interval (interval is the file space used by the GAM page to map. It is approximately 4 GB). Every index, which is allocated from a GAM interval that has more than one extent, requires an IAM page for that specific GAM interval. For all GAM interval extents, an IAM page contains one bit for each extent. A set bit shows that the particular index is given to that index. A common reason for such multiple IAM pages error that you might be encountering can be hardware failure. SQL database recovery becomes necessary for you in this case.
How to Fix Damaged MDF File? You can perform the following methods for SQL database recovery:
• Replace Damaged Hardware: First of all, you must check if there is any issue related to hardware failure. For this, you can run hardware diagnostics and check your application, Windows & SQL Server error log. If such issue exists, replace the damaged hardware (if required).
• SQL Database Recovery from Backup: If you have a clean backup for your SQL database, then you can easily restore from it. But, if no such valid backup is there, then you can use a third-party tool.
SQL Database Recovery using Third-party Tool: You can invest in an SQL MDF repair tool, which is an easy, efficient, safe and time-saving way to deal with the problem. One such powerful SQL database recovery tool is SysTools SQL Recovery software. It is a superior tool with a user-friendly interface and it employs advanced technology for efficient recovery and fast algorithms for quick MDF repair.