SQL Server 2008 Memory Usage details

Server configuration : Windows 2008 64-bit & SQL Server 2008 64-bit environment with 14 Gigs of Memory.

Max. Server Memory set to 11 Gigs.

- The task manager is showing sqlservr.exe is consuming all the 11 Gigs of memory.

- The DBCC Memory Status result from Memory Manager tab is as follows:

Memory Manager    KB
VM Reserved    14806872
VM Committed    11147312

- When I query the entire memory usage using the following script (taken from the site :http://sqlserverpedia.com/wiki/Current_Memory_Use_By_SQL_Server)

select 
	type,
	sum(virtual_memory_reserved_kb) as [VM Reserved],
	sum(virtual_memory_committed_kb) as [VM Committed],
	sum(awe_allocated_kb) as [AWE Allocated],
	sum(shared_memory_reserved_kb) as [SM Reserved], 
	sum(shared_memory_committed_kb) as [SM Committed],
	sum(multi_pages_kb) as [MultiPage Allocator],
	sum(single_pages_kb) as [SinlgePage Allocator]
from sys.dm_os_memory_clerks 
group by type
order by 8 desc

From the result set I have noticed the following heavy memory usage details for this instance.

type                                   VM Reserved    VM Committed    AWE Allocated    SM Reserved    SM Committed    MultiPage Allocator    SinlgePage Allocator
MEMORYCLERK_SQLBUFFERPOOL 14712832    11249328    0    0    0    400    0

Here, I am unable to drill down, 1. What is VM Committed ? (same result being shown in DBCC Memorystatus result set). I referred thatVM Committed: This value shows the VAS that is committed by threads that are running on this node.

From the Memory Clerk name, I can understand that this is SQL Server Bufferpool usage. But, I find an another script from the following link that is providing the database wise bufferpool memory usage. This script is querying the DMV:sys.dm_os_buffer_descriptors

------Determine SQL Server memory use by database and object

------http://www.mssqltips.com/sqlservertip/2393/determine-sql-server-memory-use-by-database-and-object/

But, as per the result of this query on this said instance, the total bufferpool usage by all the databases are around 7 Gigs only. So, what is the reason for the gap of 4 Gigs ?

How to identify which is causing this usage ? I mean to break-up for the memory usage of 11249328 KB.Thanks in advance.