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SQL IO Simulator


The SQL IO Simulator test stresses the IO subsystem by generating IO patterns similar to the IO activity of the SQL Server. The simulator creates two types of temporary files on the drives to be tested: database data files and database log files. The data files are used to read and write verifiable data pages; the log files are used to simulate the Write Ahead Logging (WAL) protocol.

Details simulates SQL threads so it has lazywriter, logwriter, checkpoint, grow/shrink, read-ahead, bulk insert, random access, and audit threads (called ‘users’). The content of the pages is random, but it can be recreated using the seed value. Every time the page is read from disk, the tool checks whether or not the buffer descriptor for this page is in the buffer pool already (the page has been read/written before). If that is the case, a replica page is created from the seed stored in the descriptor, and the pages are compared; if not, the page is checked for consistency using the checksum from the page header. If validation fails, the dump of the page is saved as SqlSimErrorDumpXXXXX.txt in the current directory, and the error is logged.


Software Requirements

The test tool requires the following Windows operating systems:

  • Windows Server 2008 R2

Hardware Requirements

The test tool requires the following hardware:

  • Device to be tested
  • Computer that meets the minimum software requirements
  • Windows keyboard
  • Two-button pointing device
  • Color display monitor capable of at least 1024 by 768 resolution, 32-bits per pixel, 60 Hz
  • Hard drive with a minimum of 20 GB available on partition C:


The test tool runs on the following processor architectures:

  • x64
  • Itanium

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Built on December 10, 2009