Comments on: SQL SERVER – Pending IO request in SQL Server – DMV

By: SQL SERVER – Weekly Series – Memory Lane – #020 | SQL Server Journey with SQL Authority

Sat, 16 Mar 2013 01:30:50 +0000

[...] SQL SERVER – Pending IO request in SQL Server – DMV “How do we know how many pending IO requests are there for database files (.mdf, .ldf) individually?” Very interesting question and indeed answer is very interesting as well. Here is the quick script which I use to find the same. It has to be run in the context of the database for which you want to know pending IO statistics. [...]

By: selvakumar

selvakumar — Mon, 26 Nov 2012 04:41:19 +0000

i like to know , how to find total time taken by io in sql server.i need to find this by query.then what is the difference between elaspsed time and io time.

By: mbourgon

mbourgon — Wed, 23 May 2012 16:36:10 +0000

Pinal, I’m using a different query that does outer joins on dm_io_pending_io_requests and dm_io_virtual_file_stats, and I’m finding slowdowns in unknown files – the io_handle doesn’t match up. Any ideas?

select
db_name(vfs.database_id) as database_name,
mf.name as logical_file_name,
pr.io_type,
io_handle,
sum(pr.io_pending_ms_ticks) as sum_io_pending_ms_ticks,
count(*) as [count]
from
sys.dm_io_pending_io_requests pr
left join sys.dm_io_virtual_file_stats(null, null) vfs on vfs.file_handle = pr.io_handle
left join sys.master_files mf on mf.database_id = vfs.database_id
and mf.file_id = vfs.file_id
where
pr.io_pending = 1
group by
db_name(vfs.database_id),
mf.name,
pr.io_type, io_handle

By: Krishnam

Krishnam — Fri, 25 Mar 2011 04:42:13 +0000

To see the slowest data file, I join the sys.dm_io_virtual_file_stats tabular function with the sys.master_files system view and calculate the average wait time.

SELECT smf.name AS InternalName
, smf.physical_name AS PhysicalFile
, smf.type_desc AS FileType
, CONVERT(NUMERIC(15,0), ((io_stall_read_ms / num_of_reads)
+ (io_stall_write_ms / num_of_writes)) / 2) AS AverageWait_ms
FROM sys.dm_io_virtual_file_stats(NULL, NULL) svs
INNER JOIN sys.master_files smf ON svs.database_id = smf.database_id
AND svs.file_id = smf.file_id
ORDER BY AverageWait_ms DESC