A data object management scheme for storing a large plurality of small data objects (e.g., image files) in small number of large object stack file for storage in secondary storage (e.g., hard disks). By storing many individual data objects in a single object stack file, the number of files stored in the secondary storage is reduced by several orders of magnitude, from the billions or millions to the hundreds or so. Index data for each object stack file is generated and stored in primary storage to allow efficient and prompt access to the data objects. Requests to store or retrieve the data objects are made using HTTP messages including file identifiers that identify the files storing the data objects and keys identifying the data objects. A file server stores or retrieves the data object from secondary storage of a file server without converting the requests to NSF or POSIX commands.