SQLIOSim – Is Error: Unable to get disk cache info really an error?


The short answer is that it is not an error and the message should be a WARNING.




I looked at the latest, internal code base it has already been changed to a WARNING.


                           if (!DeviceIoControl (volume,





                                                              sizeof (m_diskCacheInfo), 


                                                              NULL) || sizeof (m_diskCacheInfo) != dwBytes)


                                  Logger(TYPE_WARN, _T(__FILE__), __LINE__, _T(__FUNCTION__), HRESULT_FROM_WIN32 (GetLastError()),

                                                       _T(“Unable to get disk cache info for %s”), mountPoint);




The only place the returned value is used in the code is to display the possible cache settings in the SQLIOSim log. 


       Logger(TYPE_INFO, _T(__FILE__), __LINE__, _T(__FUNCTION__), 0,

                                                       _T(“DRIVE LEVEL: “)

                                                       _T(“Read cache enabled = %ls, “)

                                                       _T(“Write cache enabled = %ls”),

                                                       m_diskCacheInfo.ReadCacheEnabled ? L“Yes” : L“No”,

                                                       m_diskCacheInfo.WriteCacheEnabled ? L“Yes” : L“No”);


The SQLIOSim testing attempt will continue without any impact of this error/warning. 

Bob Dorr –  Principal SQL Server Escalation Engineer

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