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FILE_FS_SECTOR_SIZE_INFORMATION structure (ntddk.h)

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The FILE_FS_SECTOR_SIZE_INFORMATION structure is used to query physical and logical sector size information for a file system volume.

Syntax

typedef struct _FILE_FS_SECTOR_SIZE_INFORMATION {
  ULONG LogicalBytesPerSector;
  ULONG PhysicalBytesPerSectorForAtomicity;
  ULONG PhysicalBytesPerSectorForPerformance;
  ULONG FileSystemEffectivePhysicalBytesPerSectorForAtomicity;
  ULONG Flags;
  ULONG ByteOffsetForSectorAlignment;
  ULONG ByteOffsetForPartitionAlignment;
} FILE_FS_SECTOR_SIZE_INFORMATION, *PFILE_FS_SECTOR_SIZE_INFORMATION;

Members

LogicalBytesPerSector

Logical bytes per sector reported by physical storage. This is the same value as the block size for used for Logical Block Addressing (LBA).

PhysicalBytesPerSectorForAtomicity

Actual bytes per sector reported by physical storage used for an atomic write.

PhysicalBytesPerSectorForPerformance

Bytes per sector reported by physical storage for best performance.

FileSystemEffectivePhysicalBytesPerSectorForAtomicity

The portion of PhysicalBytesPerSectorForAtomicity considered as the physical sector size by the file system.

Flags

Flags for sector alignment and performance capabilities. This value is a bitwise OR combination of the following:

Value Meaning
SSINFO_FLAGS_ALIGNED_DEVICE
 Logical sectors of the storage device are aligned to physical sector boundaries.
SSINFO_FLAGS_PARTITION_ALIGNED_ON_DEVICE
 The partition is aligned to physical sector boundaries on the storage device.
SSINFO_FLAGS_NO_SEEK_PENALTY
 The storage device has no seek penalty.
SSINFO_FLAGS_PARTITION_ALIGNED_ON_DEVICE
 The storage device supports the TRIM operation.

ByteOffsetForSectorAlignment

The offset, in bytes, of the beginning of the first logical sector within the first physical sector. This member is set to SSINFO_OFFSET_UNKNOWN if proper device information is not available to calculate the value.

ByteOffsetForPartitionAlignment

The offset value, in bytes, used to align the partition to a physical sector boundary. This member is set to SSINFO_OFFSET_UNKNOWN if proper device information is not available to calculate the value.

Remarks

This information can be queried in either of the following ways:

  • Call FltQueryVolumeInformation or ZwQueryVolumeInformationFile, passing FileFsSectorSizeInformation as the value of FileInformationClass and passing a caller-allocated, FILE_FS_SECTOR_SIZE_INFORMATION-structured buffer as the value of FileInformation.
  • Create an IRP with major function code IRP_MJ_QUERY_VOLUME_INFORMATION.
  • Call FsRtlGetSectorSizeInformation with a pointer to a FILE_FS_SECTOR_SIZE_INFORMATION-structured buffer. The FileSystemEffectivePhysicalBytesPerSectorForAtomicity member will not have a value initialized by the file system when this structure is returned from FsRtlGetSectorSizeInformation. A file system driver will typically call this function and then set its own value for FileSystemEffectivePhysicalBytesPerSectorForAtomicity.
No specific access rights are required to query this information. Thus this information is available as long as the volume is accessed through an open handle to the volume itself, or to a file or directory on the volume.

The size of the buffer passed in the FileInformation parameter to FltQueryVolumeInformation or ZwQueryVolumeInformationFile must be at least sizeof (FILE_FS_SECTOR_SIZE_INFORMATION).

The file system uses the value of LogicalBytesPerSector to determine the size of an allocation unit. The LogicalBytesPerSector member of this structure is equivalent to the BytesPerSector member of the FILE_FS_SIZE_INFORMATION and FILE_FS_FULL_SIZE_INFORMATION structures.

If the system is unable to determine values for PhysicalBytesPerSectorForAtomicity and PhysicalBytesPerSectorForPerformance from the storage device, then they are set to the value of LogicalBytesPerSector.

Requirements

Requirement Value
Minimum supported client This structure is available starting with Windows 7.
Header ntddk.h (include Ntddk.h, Ntifs.h, Fltkernel.h)

See also

FILE_FS_FULL_SIZE_INFORMATION

FILE_FS_SIZE_INFORMATION

FltQueryVolumeInformation

FsRtlGetSectorSizeInformation

IRP_MJ_QUERY_VOLUME_INFORMATION

ZwQueryVolumeInformationFile