A very useful update, KB2913766, was released by Microsoft to improve storage enclosure management for Storage Spaces in Windows 8.1 and Windows Server 2012 R2.
This article introduces a hotfix that extends platform support for Storage Spaces in Windows 8.1 and Windows Server 2012 R2. After you install this hotfix, storage enclosure management is improved. The improvement is achieved by adding Storage Management Application Programming Interface (SMAPI) support for enclosure awareness that enables managing and health monitoring of just-a-bunch-of-disks (JBOD) enclosures.
The hotfix is available from Microsoft.
There is no documentation to state what the exact improvements are. I know “some” stuff but I don’t know how clear I am to share it. A search based on that “stuff” revealed nothing public.