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PREEMPTIVE_OS_GETVOLUMENAMEFORVOLUMEMOUNTPOINT

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Description:

This wait type is when a thread is calling the Windows GetVolumeNameForVolumeMountPoint function.

(Books Online description: N/A)

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Added in SQL Server version:

2008

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 458 in 2008 and 2008 R2, 506 in 2012, and 522 in 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

I have not seen this wait type be a noticeable contention point.

Note that when a thread calls out to Windows, the thread changes from non-preemptive (SQL Server controls the thread) to preemptive (Windows controls the thread) mode. The thread’s state will be listed as RUNNING, as SQL Server doesn’t know what Windows is doing with the thread.

Known occurrences in SQL Server (list number matches call stack list):

  1. Getting the volume name (in this case, as part of creating a database)
  2. Getting the volume name (in this case, as part of creating a database snapshot)
  3. Getting the volume name (in this case, as part of restoring a database backup)

And other similar call stacks.

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    ChkRawNameWithConvert+36d
    DBGetFileAttributesW+99
    FileMgr::ValidateFileName+34f
    FileMgr::ValidateFile+28
    GetFileFromFileDecl+1d5
    FileMgr::CreateFilesFromDecls+396
    CStmtCreateDB::CreateLocalDatabaseFragment+515
    DBDDLAgent::CreateDatabase+f7
    CStmtCreateDB::XretExecute+dc1
    CMsqlExecContext::ExecuteStmts<1,1>+427
    CMsqlExecContext::FExecute+a43
    CSQLSource::Execute+86c
    process_request+a57
    process_commands+4a3
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    ChkRawNameWithConvert+36d
    DBGetFileAttributesW+99
    FileMgr::ValidateFileName+34f
    FileMgr::ValidateFile+28
    GetFileFromFileDecl+1d5
    FileMgr::BuildSnapshotFileList+73f
    DBMgr::CreateSnapshotDatabase+4c7
    CStmtCreateDB::CreateSnapshot+503
    CStmtCreateDB::XretExecute+50f
    CMsqlExecContext::ExecuteStmts<1,1>+427
    CMsqlExecContext::FExecute+a43
    CSQLSource::Execute+86c
    process_request+a57
    process_commands+4a3
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  3. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    ChkRawNameWithConvert+36d
    DBGetFileAttributesW+99
    FileMgr::ValidateFileName+34f
    RestoreContainer::ValidateTargetForCreation+1d0
    BackupFileDesc::PlanContainerPreparation+3c7
    BackupOperation::PlanPhysicalConfiguration+60c
    BackupOperation::PlanFullRestore+a7
    BackupOperation::PlanRestore+be4
    BackupOperation::Restore+262
    BackupEntry::RestoreDatabase+254
    CStmtLoadDb::XretExecute+125
    CMsqlExecContext::ExecuteStmts<1,1>+427
    CMsqlExecContext::FExecute+a43
    CSQLSource::Execute+86c
    process_request+a57
    process_commands+4a3
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab