The storage density of a single enterprise disk drive has grown several orders of magnitude since its birth in the late 1950’s while the disk drive’s block interface has remained essentially the same. Challenging this interface is an increasing demand among enterprise users for storage subsystems that can scale economically and efficiently into the multiple petabyte range. As that happens, the block storage interface is increasingly seen as an impediment to the development of petabyte-scale disk storage arrays. Traditional NAS filers also suffer from the same inability to scale for two reasons: First, capacity of non-clustered filers is limited to a single NAS array; second, even “scale out” NAS that leverages clustered controllers to go beyond the single array limitation uses block storage behind these controllers.
A far more scalable and versatile interface based on stored objects, rather than blocks, can remove this impediment. Object-based storage is now coming of age since its inception in the late 1990’s and is taking its place alongside block (DAS and SAN) and file-based (NAS) storage. The commonly used name for this technology is Object-based Storage Device (OSD).