object storage device (OSD)

An object-based storage device or object storage device (OBSD or OSD) is a computer storage system that organizes data into containers called objects that a user or application determines are related. 

The objects reside in a flat address space where they all exist at the same level and cannot be placed inside one another. Each one has a unique object identifier (OID) that allows a server or end user to retrieve it without knowing the physical location of the data it contains.

An OSD allocates space for objects and manages lower-level space and security functions. Users and applications interface with objects through an API (application program interface) or by means of HTTP (hypertext transfer protocol). Public cloud service providers typically implement APIs to give users file or block access to OSD storage on the back end. For private clouds and archives, users either handle the APIs themselves or use an OSD that includes front-end functionality. Another alternative is to implement a cloud gateway that provides the appropriate protocols for user interface to back-end object storage.

Object storage may work better than network-attached storage (NAS) architectures for large unstructured data sets in applications such as medical imaging, movies, entertainment, and cloud storage. Object storage supports growth without significant performance degradation, and OSDs can be scaled geographically. Distributing copies of data across storage nodes can enhance data protection. In addition, OSDs can improve data resiliency with erasure coding.