File Instance

A file instance corresponds to the physical representation of a file on a file system. It is characterized by information such as the file name, creation date, last modification date, etc.

Where the file describes the content, the file instance describes the container and its storage context.

Multiple instances can exist for the same file within Djehooty. For example, if the same file is imported into Djehooty from two different storage media, each import creates a new instance, all linked to the same file (same SHA-256 hash).

This mechanism avoids duplication of identical files while preserving valuable information about their origin and storage context. Metadata from different file systems can thus enrich the knowledge about a given file.

This concept is introduced to address situations where one or more files circulate within a family and end up scattered across multiple digital collections. If a genealogist later retrieves and imports files from several collections of this family, they may end up importing the same files in multiple copies. Information from the file system (creation and modification dates) may differ depending on the collections and provide the genealogist with important information, particularly for dating documents.