Error in SQL Server error log:
SQL Server has encountered x occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [Drive:\MSSQL\MSSQL.1\MSSQL\Data\xyz.mdf] in database [database]. The OS file handle is 0x00000000. The offset of the latest long I/O is: 0x00000000000000
NOTE: The source of these message are from SQL Server, not LiteSpeed.
To troubleshoot, use Performance Monitor for: Logical Disk –> Drive(s) experiencing I/O stall –> Avg. Disk sec/Transfer
Additional Information:
This concept is also detailed in:
Also:
There are some sample scripts available at http://technet.microsoft.com/en-us/library/bb838723(office.12).aspx to find I/O bound queries and batches/requests that are generating the most I/O.
Refer the KB article below for details troubleshooting guide on Stuck and Stalled I/O: http://support.microsoft.com/kb/897284/en-us
You should always check the time when this message is reported and check whether you have a maintenance job running at that point. It could be a Full Backup, Update Statistics, Rebuild/Reorganize indexes running at that point which does a heavy I/O and because of which SQL Server experiences stalled I/O
Further reads:
http://technet.microsoft.com/en-in/library/cc966414(en-us).aspx - Physical Database Storage Design
http://technet.microsoft.com/en-us/library/aa997558(EXCHG.65).aspx - Ruling Out Disk-Bound Problems
http://www.microsoft.com/downloads/en/details.aspx?familyid=9a8b005b-84e4-4f24-8d65-cb53442d9e19&displaylang=en - SQLIO Disk Subsystem Benchmark Tool
http://msdn.microsoft.com/en-us/library/aa365199(v=VS.85).aspx - I/O Concepts (Windows)
