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