In many situations, even minor actions can change a file's access time. The following scenarios will modify file access time, making it impractical to maintain custom access time.
Common Scenarios That Change Access Time
1. Reading File Content
Opening and viewing files:
- Opening files with Notepad, Word, or other programs
- Programs calling ReadFile() or similar APIs to read file data
- Exception: If the system has disabled Last Access Time updates (common in Windows 7+ for performance optimization), it may not update
2. Copying or Moving Files
File operations:
- Copying files: The target file's access date will be updated to the new operation time
- Moving files (same partition): Usually preserves original time attributes (but may update in some cases)
- Moving files (cross-partition): Equivalent to copy + delete, target file access time may update
3. Program Scanning or File Traversal
System operations:
- Antivirus software scanning
- File indexing services (Windows Search)
- File Explorer previewing files
- Command-line tools (like dir) traversing directories may trigger updates if not using specific parameters (e.g., dir /T:W only reads modification date)
4. File Attributes or Metadata Access
Metadata operations:
- Viewing file properties (right-click → Properties) may update access time (depending on system configuration)
- Reading file permissions, size, and other metadata (e.g., through GetFileAttributes())
5. Other Operations
Additional scenarios:
- File compression/decompression
- Encryption/decryption
- Some backup software or sync tools reading files
Why This Makes Access Time Impractical
Constant Changes
Access times change frequently during normal computer usage, making any custom access time short-lived.
System Optimizations
Many modern operating systems disable access time updates by default for performance reasons:
- Windows 7+ often has DisableLastAccessUpdate enabled
- Linux systems may mount filesystems with noatime option
- macOS has similar optimizations
Limited Practical Value
Unlike created time and modified time, access time:
- Don't represent meaningful file history
- Are easily corrupted by routine operations
Our Recommendation
We focus on created time and modified time because they:
- Represent meaningful file history
- Are more stable and predictable
- Provide real value for file organization
- Are less likely to be accidentally changed by routine operations
This approach ensures that the timestamps you set will remain meaningful and useful over time.