Note on <Professional SQL Server 2012 Internals And Troubleshooting> - 01

Chapter 1: SQL Server Architecture

SELECT COUNT(*)*8/1024 AS 'Cached Size (MB)'
	,CASE database_id
		WHEN 32767 THEN 'ResourceDb'
		ELSE db_name(database_id)
	END AS 'Database'
FROM sys.dm_os_buffer_descriptors
GROUP BY db_name(database_id),database_id
ORDER BY 'Cached Size (MB)' DESC

SELECT db_name(database_id) AS 'Database',COUNT(page_id) AS 'Dirty Pages'
FROM sys.dm_os_buffer_descriptors
WHERE is_modified =1
GROUP BY db_name(database_id)
ORDER BY COUNT(page_id) DESC

SELECT max_workers_count
FROM sys.dm_os_sys_info

SELECT COUNT(*) FROM sys.dm_os_workers