IO stalls

-- Good < 5 msec
-- ideal value < 20 msec

SELECT files.physical_name, files.name,
stats.num_of_writes, (1.0 * stats.io_stall_write_ms / stats.num_of_writes) AS avg_write_stall_ms,
stats.num_of_reads, (1.0 * stats.io_stall_read_ms / stats.num_of_reads) AS avg_read_stall_ms
FROM sys.dm_io_virtual_file_stats(null, NULL) as stats
INNER JOIN master.sys.master_files AS files
ON stats.database_id = files.database_id
 AND stats.file_id = files.file_id
 WHERE files.type_desc = 'ROWS'