{"name":"Average IO stalls","description":"<strong>Explanation:<\/strong> This is a general indicator of performance problems. High stall times indicate I\/O problems, which can be attributed to busy physical disks or queries that return large data sets to the client.\r\n\r\n<strong>Guideline values: <\/strong>The ideal value for this metric should be less than 100, but this is just a rule-of-thumb. Higher values may be acceptable for your organization.\r\n\r\n<strong>Check also:<\/strong>\r\n<ul>\r\n\t<li><strong>Disk avg. read time<\/strong><\/li>\r\n\t<li><strong>Disk avg. write time<\/strong><\/li>\r\n\t<li><strong>Avg. disk queue length<\/strong><\/li>\r\n<\/ul>\r\n<strong>Possible solutions:<\/strong> \r\nIO Stalls are affected by three possible factors:<ol> \t<li>poorly performing disk subsystem (such as a misconfigured SAN)<\/li>\r\n\t<li>poorly defined queries<\/li>\r\n\t<li>overloaded disks (\u201cdata bursts\u201d)<\/li><\/ol>\r\n<p>Solutions may involve allocating new hardware resources in addition to performance tuning of individual queries.<\/p>\r\n\r\n<strong>More information:<\/strong>\r\n\r\n<p><a href=\"http:\/\/troubleshootingsql.com\/2009\/12\/30\/disk-contention-issues\/\">Wikis: Disk Contention Issues<\/a><\/p>\r\n\r\n<p><a href=\"http:\/\/blogs.msdn.com\/b\/sqlsakthi\/archive\/2011\/02\/09\/troubleshooting-sql-server-i-o-requests-taking-longer-than-15-seconds-i-o-stalls-amp-disk-latency.aspx\">Troubleshooting SQL Server I\/O requests taking longer than 15 seconds - I\/O stalls &amp; Disk latency<\/a><\/p>\r\n\r\n","tsql":"SELECT  CAST(SUM(io_stall_read_ms + io_stall_write_ms) \/\r\n             SUM(1.0 + num_of_reads + num_of_writes) AS NUMERIC(10, 1)\r\n        ) AS [avg_io_stall_ms]\r\nFROM    sys.dm_io_virtual_file_stats(DB_ID(), NULL)\r\nWHERE   FILE_ID <> 2;\r\n","instances":true,"frequency":60,"databases":{"mode":0},"rateofchange":false,"metricenabled":true,"noalertremark":"An alert is not required","alertdescription":"","aboveorbelow":"above","collections":1,"alertenabled":false,"_thresholds_high":{"selected":false},"_thresholds_medium":{"selected":false},"_thresholds_low":{"selected":false},"targetentitytype":0}