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STG_E_MEDIUMFULL
The IStorage interface supports the creation and management of structured storage objects. Structured storage allows hierarchical storage of information within a single file, and is often referred to as "a file system within a file". Elements of a structured storage object are storages and streams. Storages are analogous to directories, and streams are analogous to files. Within a structured storage there will be a primary storage object that may contain substorages, possibly nested, and streams. Storages provide the structure of the object, and streams contain the data, which is manipulated through the IStream interface.
The IStorage interface provides methods for creating and managing the root storage object, child storage objects, and stream objects. These methods can create, open, enumerate, move, copy, rename, or delete the elements in the storage object.
An application must release its IStorage pointers when it is done with the storage object to deallocate memory used. There are also methods for changing the date and time of an element.
There are a number of different modes in which a storage object and its elements can be opened, determined by setting values from STGM Constants. One aspect of this is how changes are committed. You can set direct mode, in which changes to an object are immediately written to it, or transacted mode, in which changes are written to a buffer until explicitly committed. The IStorage interface provides methods for committing changes and reverting to the last-committed version. For example, a stream can be opened in read-only mode or read/write mode. For more information, see STGM Constants.
Other methods provide access to information about a storage object and its elements through the STATSTG structure.