An Object-based Storage Device (OSD) enables the creation of self-managed, shared and secure storage for storage networks. This moves lower-level functionalities such as space management into the storage device itself, where the device is accessed through a standard object interface. The standard OSD interface was defined in the SNIA OSD working group.. The protocol is embodied over SCSI and defines a new set of SCSI commands, standardized as a T10 protocol. Work continues on a second generation of the command set, Object-Based Storage Devices - 2 (OSD-2)

An object store raises the level of abstraction presented by today's block devices. Instead of presenting the abstraction of a logical array of unrelated blocks, addressed by their index in the array (i.e., their Logical Block Address (LBA)), an object store appears as a collection of objects. An individual object is a container of storage (object-data and object-meta-data) that exposes an interface similar to a file, and presents the abstraction of a sparsely allocated array of bytes indexed from zero to infinity.

The object store provides "fine-grain" object-level security, improved scalability by localizing space management, and improved management by allowing end-to-end management of semantically-meaningful entities.

A more in-depth description can be found at the following sites:

http://www.pdl.cmu.edu/PDL-FTP/Storage/MesnierIEEE03_abs.html

http://developers.sun.com/solaris/articles/osd.html