Techniques are disclosed for providing a file system interface for an object store intended to support simultaneous access to objects stored in the object store by multiple clients. In accordance with one method, an abstraction of a root directory to a hierarchical namespace for the object store is exposed to clients. The object store is backed by a plurality of physical storage devices housed in or directly attached to the plurality of host computers and internally tracks its stored objects using a flat namespace that maps unique identifiers to the stored objects. The creation of top-level objects appearing as subdirectories of the root directory is enabled, wherein each top-level object represents a separate abstraction of a storage device having a separate namespace that can be organized in accordance with any designated file system.