InstantForum.NET v2.9.0SQLServerCentralhttp://www.sqlservercentral.com/Forums/notifications@sqlservercentral.comTue, 18 Jun 2013 23:21:39 GMT20http://www.sqlservercentral.com/Forums/Topic1400976-377-1.aspxYou are welcome.Fri, 28 Dec 2012 10:57:36 GMTSQLRNNRhttp://www.sqlservercentral.com/Forums/Topic1400976-377-1.aspxHoly Moses.so obvious when you stated it.Thank you very much......GAJFri, 28 Dec 2012 10:54:46 GMTGregoryAJacksonhttp://www.sqlservercentral.com/Forums/Topic1400976-377-1.aspxThe SAN numbers are reporting just the time in the SAN. The numbers from SQL Server report the time it left SQL Server until it gets back to SQL Server. So the difference here is the time outside of SQL Server and outside of SAN. This can be the OS but is more likely the connection between the server and the SAN.Fri, 28 Dec 2012 10:49:05 GMTSQLRNNRhttp://www.sqlservercentral.com/Forums/Topic1400976-377-1.aspxHey Folks,I'm a bit confused regarding the Latency numbers reported by SQL Server Virtual File Stats (sys.dm_io_virtual_file_stats) compared to the Latency reported by the SAN Itself.According to my Systems Engineers, the SAN is only reporting "avg read\write latency" of ~20 whereas teh Virtual File Stats Read Latency of 93 and Write Latency of 87.How are we getting such a vastly different number and how can I get an apples to apples comparison?the query I'm using is below (the Systems Engineers are using the Tools Built into the SAN to get their figures). The SAN is a NetApp 2040.\SELECT sample_ms,DB_NAME(vfs.database_id) AS database_name ,vfs.database_id ,vfs.FILE_ID ,io_stall_read_ms / NULLIF(num_of_reads, 0) AS avg_read_latency ,io_stall_write_ms / NULLIF(num_of_writes, 0)AS avg_write_latency ,io_stall / NULLIF(num_of_reads + num_of_writes, 0)AS avg_total_latency ,num_of_bytes_read / NULLIF(num_of_reads, 0)AS avg_bytes_per_read ,num_of_bytes_written / NULLIF(num_of_writes, 0)AS avg_bytes_per_write ,vfs.io_stall ,vfs.num_of_reads ,vfs.num_of_bytes_read ,vfs.io_stall_read_ms ,vfs.num_of_writes ,vfs.num_of_bytes_written ,vfs.io_stall_write_ms ,size_on_disk_bytes / 1024 / 1024. AS size_on_disk_mbytes ,physical_nameFROM sys.dm_io_virtual_file_stats(NULL, NULL) AS vfsJOIN sys.master_files AS mf ON vfs.database_id = mf.database_idAND vfs.FILE_ID = mf.FILE_IDwhere vfs.database_id =5 ORDER BY avg_total_latency DESCThanksGreg JacksonFri, 28 Dec 2012 10:36:44 GMTGregoryAJackson