USN_JOURNAL_DATA_V2 structure

Represents an update sequence number (USN) change journal, its records, and its capacity. This structure is the output buffer for the FSCTL_QUERY_USN_JOURNAL control code.

Syntax

typedef struct USN_JOURNAL_DATA_V2 {
  DWORDLONG UsnJournalID;
  USN       FirstUsn;
  USN       NextUsn;
  USN       LowestValidUsn;
  USN       MaxUsn;
  DWORDLONG MaximumSize;
  DWORDLONG AllocationDelta;
  WORD      MinSupportedMajorVersion;
  WORD      MaxSupportedMajorVersion;
  DWORD     Flags;
  DWORDLONG RangeTrackChunkSize;
  LONGLONG  RangeTrackFileSizeThreshold;
}  *PUSN_JOURNAL_DATA_V2;

Members

UsnJournalID

The current journal identifier. A journal is assigned a new identifier on creation and can be stamped with a new identifier in the course of its existence. The NTFS file system uses this identifier for an integrity check.

FirstUsn

The number of first record that can be read from the journal.

NextUsn

The number of next record to be written to the journal.

LowestValidUsn

The first record that was written into the journal for this journal instance. Enumerating the files or directories on a volume can return a USN lower than this value (in other words, a FirstUsn member value less than the LowestValidUsn member value). If it does, the journal has been stamped with a new identifier since the last USN was written. In this case, LowestValidUsn may indicate a discontinuity in the journal, in which changes to some or all files or directories on the volume may have occurred that are not recorded in the change journal.

MaxUsn

The largest USN that the change journal supports. An administrator must delete the change journal as the value of NextUsn approaches this value.

MaximumSize

The target maximum size for the change journal, in bytes. The change journal can grow larger than this value, but it is then truncated at the next NTFS file system checkpoint to less than this value.

AllocationDelta

The number of bytes of disk memory added to the end and removed from the beginning of the change journal each time memory is allocated or deallocated. In other words, allocation and deallocation take place in units of this size. An integer multiple of a cluster size is a reasonable value for this member.

MinSupportedMajorVersion

The minimum version of the USN change journal that the file system supports.

MaxSupportedMajorVersion

The maximum version of the USN change journal that the file system supports.

Flags

Whether or not range tracking is turned on. The following are the possible values for the Flags member.

Value Meaning
0x00000000
Range tracking is not turned on for the volume.
FLAG_USN_TRACK_MODIFIED_RANGES_ENABLE
0x00000001
Range tracking is turned on for the volume.

RangeTrackChunkSize

The granularity of tracked ranges. Valid only when you also set the Flags member to FLAG_USN_TRACK_MODIFIED_RANGES_ENABLE.

RangeTrackFileSizeThreshold

File size threshold to start tracking range for files with equal or larger size. Valid only when you also set the Flags member to FLAG_USN_TRACK_MODIFIED_RANGES_ENABLE.

Requirements

   
Windows version Windows 8.1 [desktop apps only] Windows Server 2012 R2 [desktop apps only]
Header winioctl.h (include Windows.h)

See Also

FSCTL_QUERY_USN_JOURNAL

USN_JOURNAL_DATA_V0

USN_JOURNAL_DATA_V1

Volume Management Structures