You manage a SQL Server 2012 instance that contains a database named DB1. Users report that some
queries to DB1 take longer than expected. Although most queries run in less than one second, some queries
take up to 20 seconds to run. You need to view all of the performance statistics for each database file. Which
method should you use?
A.
Examine the Data File I/O pane in Activity Monitor.
B.
Query the sys.dm_io_virtual_file_stats dynamic management function.
C.
Query the sys.dm_os_performance_counters dynamic management view.
D.
Query the sys.dm_os_tasks dynamic management view.
Explanation:
http://technet.microsoft.com/en-us/library/ms190326.aspx
http://www.mssqltips.com/sqlservertip/1416/gather-io-statistics-down-to-the-sql-server-database-file-level/