What is Object Storage?

Object Storage is a method of storing and subsequently retrieving sets of data as collections of single, uniquely identifiable indivisible items or objects. It applies to any forms of data that can be wrapped up and managed as an object.

Objects are treated as an atomic unit. There is no structure corresponding to a hierarchy of directories in a file system; each object is uniquely identified in the system by a unique object identifier.

When you create an object on this type of storage, the entire set of data is handled and processed without regard to what sub-parts it may have. When reading from object storage, you can read either the whole object, or ask to read parts of it. There is often no capability to update to the object or parts of the object; the entire object is usually required to be re-written. Most object storage allows for objects to be deleted.

Object storage often supports meta-data. This is data that is part of the object, but that is in addition to the object ID and the data. It is often expressed as an attribute-value pair; for instance, an attribute of COLOR in our collection of objects may have the value RED for some objects and BLUE for others. These permit collections of objects, individually addressable by their object ID, to be searched, filtered and read in groups without needing to know the specific object IDs.

What objects contain is not important to the storage system. They can be simple sets of data, files, entire file systems, videos, virtual machines or containers, databases, the list is endless, since the storage system simply sees and manages the object as an object ID that is associated with a chunk of data.

How objects are stored is not important to the application. Many systems use file or block-based storage; some are specifically designed with devices that directly support objects. Regardless of how they are stored, all object storage systems support simple APIs to create, read and delete objects, and to search meta-data. Some of the better known are the SNIA’s Cloud Data Management Interface (CDMI) and Amazon’s S3 that operate through the HTTP protocol; this makes object storage attractive for Web and cloud use.

For more information, we recommend that you take a look at the informative SNIA webcast, “Object Storage: What, How and Why.” 

 


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