Where is the filename usually stored in a data storage system or file repository?

In data storage systems or file repositories, the filename is usually stored in the object's metadata or in a record that describes the file. Metadata can be stored in a database, indexes, or in special tables associated with the file system or storage system.

For example, in object storage systems (like Amazon S3), the filename (object key) is part of the metadata and is used to access the file. In traditional file systems, the filename is stored in a directory, which contains a list of files and their attributes.

Thus, the filename is typically stored in a metadata structure associated with the file or object in storage.