MSSQLSERVER_833

  • Article

Details
Product Name SQL Server
Event ID 833
Event Source MSSQLSERVER
Component SQLEngine
Symbolic Name BUF_LONG_IO
Message Text SQL Server has encountered %d occurrence(s) of I/O requests taking longer than %d seconds to complete on file [%ls] in database[%ls] (%d). The OS file handle is 0x%p. The offset of the latest long I/O is: %#016I64x.

Explanation

This message indicates that SQL Server has issued a read or write request from disk, and that the request has taken longer than 15 seconds to return. This error is reported by SQL Server and indicates a problem with the IO subsystem.

Possible Causes

This problem can be caused system performance issues, hardware errors, firmware errors, device driver problems, or filter driver intervention in the IO process.

User Action

Troubleshoot this error by examining the system event log for hardware-related error messages. Also, examine hardware-specific logs if they are available.

Use Performance Monitor to examine the following counters:

  • Average Disk Sec/Transfer

  • Average Disk Queue Length

  • Current Disk Queue Length

For example, the Average Disk Sec/Transfer time on a computer that is running SQL Server is typically less than 15 milliseconds. If the Average Disk Sec/Transfer value increases, this indicates that the I/O subsystem is not optimally keeping up with the I/O demand.

Note

Disk access can be slowed by an antivirus program. To increase access speed, exclude the SQL Server data files that are specified in the error message from active virus scans.

For more information about I/O errors, see Microsoft SQL Server I/O Basics, Chapter 2 and the Knowledge Base article at https://support.microsoft.com/kb/897284.