NTFS File System Reference

This document provides a comprehensive reference for the New Technology File System (NTFS), the standard file system for Windows operating systems.

Overview

NTFS is a high-performance file system that provides robust support for a wide range of features, including security, fault tolerance, and large storage capacities. It replaced the FAT file system in newer versions of Windows.

Key Features

  • Journaling: Records file system changes before they are committed, allowing for faster recovery in case of system crashes.
  • File and Folder Permissions: Granular control over access to files and directories using Access Control Lists (ACLs).
  • Compression: Built-in support for compressing files and folders to save disk space.
  • Encryption (EFS): Encrypting File System allows users to encrypt files to protect sensitive data.
  • Disk Quotas: Administrators can manage storage space allocation for users.
  • Hard Links and Junctions: Support for creating multiple directory entries that point to the same file or directory.
  • Alternate Data Streams (ADS): Allows associating metadata with files beyond the standard attributes.

File System Structure

NTFS organizes data using a Master File Table (MFT) which contains records for every file and directory. Key components include:

  • Master File Table (MFT): A database containing information about all files and directories.
  • Attribute List: Stores metadata and attributes for files.
  • Bitmap: Tracks the allocation status of clusters on the disk.
  • Boot Sector: Contains information necessary to boot the operating system.

Metadata and Attributes

Each file or directory on an NTFS volume has a set of attributes that define its properties. Common attributes include:

Attribute Name Description
$STANDARD_INFORMATION Stores basic file information like timestamps, file size, and flags.
$FILE_NAME Contains the file's name and parent directory information.
$DATA Holds the actual content of the file. For small files, this can be resident within the MFT.
$SECURITY_DESCRIPTOR Defines the security permissions for the file or directory.
$ATTRIBUTE_LIST Used when a file has too many attributes to fit in the initial MFT record.
$INDEX_ROOT / $INDEX_ALLOCATION Used by directories to index their contents.

Security and Permissions

NTFS uses Access Control Lists (ACLs) to manage security. An ACL is a list of Access Control Entries (ACEs), each specifying permissions for a particular security principal (user or group).

Note: Understanding NTFS permissions is crucial for secure file system management. Incorrect configuration can lead to unauthorized access or denial of service.

Related APIs

Developers can interact with NTFS features through various Windows APIs:

  • File Management Functions: CreateFile, ReadFile, WriteFile, SetFileAttributes.
  • Security Functions: GetSecurityInfo, SetSecurityInfo, AccessCheck.
  • Volume Information: GetVolumeInformation.
  • Directory Management: FindFirstFile, FindNextFile.

For more detailed information on specific API functions, please refer to the respective API documentation.

Caution: Direct manipulation of NTFS structures is generally not recommended for standard application development. Use the provided Windows APIs to ensure compatibility and stability.