The following features of the Overlay Filesystem are briefly described below.

Copy on Write
Inode Mapping
Change Tracking
Storage System
File Attributes

Feature: Overlay

Status Released
Description The contents of one filesystem can be overlayed with the contents of another filesystem.
Details Overlay

Feature: Copy on Write

Status Released
Description Files in the base filesystem are copied into the storage filesystem on write so that the original files remain intact while the processes accessing those files can modify their content as-needed.
Details Copy on Write

Feature: Inode Mapping

Status Released
Description Inodes in the base and storage filesystems are mapped to overlay filesystem inodes by device and inode number.
Details Inode Mapping

Feature: Change Tracking

Status Released
Description Changes to inode attributes and directory contents are tracked by the Overlay Filesystem for the base filesystem.
Details Change Tracking

Feature: Storage System

Status Partially Implemented
Description Storage for the Overlay Filesystem's inodes, mappings, directory contents, and file contents can be supplied by separate subsystems using the Storage System registration.
Details Storage System

Feature: File Attributes

Status Under Consideration
Description Files can be tagged with attribute name/value pairs transparent to the filesystem user. These attributes can be retrieved using special commands or library calls.
Details File Attributes

Last Updated: Feburary 21, 2003