IAM pages in sql server

When we are creating a table in sql server, it creates a whole hierarchy Object, partition and Allocation units. Unit store the data type.

For the entire allocation unit sql server create the separate IAM pages.

  

In short a heap/B tree structure can have minimum of one IAM page and maximum of (No. of partition X 3) IAM pages. If the tables grow further and pages allocated from different GAM interval, more IAM pages will be added. These IAM pages need to be linked together and this list is called IAM chain.

DBCC traceon(3604) DBCC ind('Test','Employee',-1)

IAM page ID is 8 in this example.