Windows Projected File System glossary

Special terms used in ProjFS.

backing store

Provider-maintained hierarchical data that is projected into the file system as files and directories.

dirty placeholder

A file or directory that has been locally modified and is no longer a cache of its state in the provider's store. See Cache State in the Virtualization Root.

full file/directory

A file or directory that was created in the local file system, or a file that has been modified, making it no longer a cache of its state in the backing store. See Cache State in the Virtualization Root.

hydrated placeholder

A file whose content and metadata have been cached to disk. See Cache State in the Virtualization Root.

placeholder

A file or directory that is not fully present on disk. See Cache State in the Virtualization Root.

tombstone

A special hidden placeholder that represents an item that has been deleted from the local file system. See Cache State in the Virtualization Root.

virtual file/directory

A file or directory that does not physically exist on disk, but is projected into enumeration results. See Cache State in the Virtualization Root.

virtualization instance

An in-memory object that manages communication between the provider and ProjFS for the set of files and directories located under a particular virtualization root.

virtualization root

A directory in the file system under which the provider's data is projected.