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ns-ntdddisk-_disk_performance.md

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UID title description old-location tech.root ms.date keywords ms.keywords req.header req.include-header req.target-type req.target-min-winverclnt req.target-min-winversvr req.kmdf-ver req.umdf-ver req.ddi-compliance req.unicode-ansi req.idl req.max-support req.namespace req.assembly req.type-library req.lib req.dll req.irql targetos req.typenames f1_keywords topic_type api_type api_location api_name
NS:ntdddisk._DISK_PERFORMANCE
_DISK_PERFORMANCE (ntdddisk.h)
The DISK_PERFORMANCE structure is used in conjunction with the IOCTL_DISK_PERFORMANCE request to collect summary disk statistics for purposes of measuring disk performance.
storage\disk_performance.htm
storage
03/29/2018
DISK_PERFORMANCE structure
*PDISK_PERFORMANCE, DISK_PERFORMANCE, DISK_PERFORMANCE structure [Storage Devices], PDISK_PERFORMANCE, PDISK_PERFORMANCE structure pointer [Storage Devices], _DISK_PERFORMANCE, ntdddisk/DISK_PERFORMANCE, ntdddisk/PDISK_PERFORMANCE, storage.disk_performance, structs-disk_64493b27-dce7-4976-9519-c7324bd09b69.xml
ntdddisk.h
Ntdddisk.h
Windows
Windows
DISK_PERFORMANCE, *PDISK_PERFORMANCE
_DISK_PERFORMANCE
ntdddisk/_DISK_PERFORMANCE
PDISK_PERFORMANCE
ntdddisk/PDISK_PERFORMANCE
DISK_PERFORMANCE
ntdddisk/DISK_PERFORMANCE
APIRef
kbSyntax
HeaderDef
ntdddisk.h
_DISK_PERFORMANCE
PDISK_PERFORMANCE
DISK_PERFORMANCE

_DISK_PERFORMANCE structure

-description

The DISK_PERFORMANCE structure is used in conjunction with the IOCTL_DISK_PERFORMANCE request to collect summary disk statistics for purposes of measuring disk performance.

-struct-fields

-field BytesRead

Contains a cumulative count of bytes read from the disk since the performance counters were enabled.

-field BytesWritten

Contains a cumulative count of bytes written to the disk since the performance counters were enabled.

-field ReadTime

Contains a cumulative time, expressed in increments of 100 nanoseconds, spent on disk reads since the performance counters were enabled.

-field WriteTime

Contains a cumulative time, expressed in increments of 100 nanoseconds, spent on disk reads since the performance counters were enabled.

-field IdleTime

Contains a cumulative time, expressed in increments of 100 nanoseconds, since the performance counters were enabled in which there was no disk activity.

-field ReadCount

Contains the number of disk accesses for reads since the performance counters were enabled.

-field WriteCount

Contains the number of disk accesses for writes since the performance counters were enabled.

-field QueueDepth

Contains a snapshot of the number of queued disk I/O requests at the time that the query for performance statistics was performed.

-field SplitCount

Contains the number of disk accesses by means of an associated IRP since the performance counters were enabled.

-field QueryTime

Contains a timestamp indicating the system time at the moment that the query took place. System time is a count of 100-nanosecond intervals since January 1, 1601. System time is typically updated approximately every ten milliseconds. For more information about system time, see KeQuerySystemTime.

-field StorageDeviceNumber

Contains a unique number assigned to every disk or volume across a particular storage type. The storage types are disk.sys, ftdisk.sys, and dmio.sys.

-field StorageManagerName

Contains an 8-character string that indicates which device driver provided the performance statistics. In Windows 2000, this can be either "LogiDisk" for the driver logidisk.sys or "PhysDisk" for the driver physdisk.sys. These drivers collect performance statistics for devices and physical disks respectively. In Windows XP and later operating systems, this can be any of the following three strings: "FTDISK" for the driver ftdisk.sys, "DMIO" for the driver dmio.sys, or PARTMGR" for the driver partmgr.sys. These three drivers collect performance statistics for basic disk volumes, dynamic disk volumes, and physical disks respectively. Note that these strings are 8-character case-sensitive strings with blank fill. For example, in the case of the string "FTDISK", the StorageManagerName character array should contain two trailing blanks ("FTDISK"), and in the case of the string "DMIO", the array should contain four trailing blanks ("DMIO").

-remarks

Counting halts whenever the performance counters are disabled, but the counters are not reset, so the cumulative values assigned to the structure members might potentially reflect disk activity across several enablings and disablings of the counters.

-see-also

IOCTL_DISK_PERFORMANCE

IOCTL_DISK_PERFORMANCE_OFF