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DEVICE_LB_PROVISIONING_DESCRIPTOR structure (winioctl.h)

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The DEVICE_LB_PROVISIONING_DESCRIPTOR structure is one of the query result structures returned from an IOCTL_STORAGE_QUERY_PROPERTY request. This structure contains the thin provisioning capabilities for a storage device.

Syntax

typedef struct _DEVICE_LB_PROVISIONING_DESCRIPTOR {
  DWORD     Version;
  DWORD     Size;
  BYTE      ThinProvisioningEnabled : 1;
  BYTE      ThinProvisioningReadZeros : 1;
  BYTE      AnchorSupported : 3;
  BYTE      UnmapGranularityAlignmentValid : 1;
  BYTE      GetFreeSpaceSupported : 1;
  BYTE      MapSupported : 1;
  BYTE      Reserved1[7];
  DWORDLONG OptimalUnmapGranularity;
  DWORDLONG UnmapGranularityAlignment;
  DWORD     MaxUnmapLbaCount;
  DWORD     MaxUnmapBlockDescriptorCount;
} DEVICE_LB_PROVISIONING_DESCRIPTOR, *PDEVICE_LB_PROVISIONING_DESCRIPTOR;

Members

Version

Contains the size of this structure, in bytes. The value of this member will change as members are added to the structure.

Size

Specifies the total size of the data returned, in bytes. This may include data that follows this structure.

ThinProvisioningEnabled

The thin provisioning–enabled status.

Value Meaning
0
 Thin provisioning is disabled.
1
 Thin provisioning is enabled.

ThinProvisioningReadZeros

Reads to unmapped regions return zeros.

Value Meaning
0
 Data read from unmapped regions is undefined.
1
 Reads return zeros.

AnchorSupported

Deterministic read after trim support.

Value Meaning
0
 Deterministic read after trim is not supported.
1
 Deterministic read after trim is supported.

UnmapGranularityAlignmentValid

The validity of unmap granularity alignment for the device.

Value Meaning
0
 Unmap granularity alignment is not valid.
1
 Unmap granularity alignment is valid.

GetFreeSpaceSupported

MapSupported

Reserved1[7]

Reserved.

OptimalUnmapGranularity

The optimal number of logical sectors for unmap granularity for the device.

UnmapGranularityAlignment

The current value, in logical sectors, set for unmap granularity alignment on the device.

MaxUnmapLbaCount

Starting in Windows 10: The maximum number of LBAs that can be unmapped in a single unmap command, in logical blocks.

MaxUnmapBlockDescriptorCount

Starting in Windows 10: The maximum number of descriptors allowed in a single unmap command.

Remarks

This structure is returned from a IOCTL_STORAGE_QUERY_PROPERTY request when the PropertyId member of STORAGE_PROPERTY_QUERY is set to StorageDeviceLBProvisioningProperty.

If UnmapGranularityAlignmentValid = 0, then any code using UnmapGranularityAlignment should assume it has a value of 0.

Requirements

Requirement Value
Minimum supported client Windows 8 [desktop apps only]
Minimum supported server Windows Server 2012 [desktop apps only]
Header winioctl.h (include Windows.h)

See also

Disk Management Structures

IOCTL_STORAGE_QUERY_PROPERTY

STORAGE_PROPERTY_QUERY