Object storage, also called object-based storage, is a generic term that describes an approach to addressing and manipulating discrete units of storage called objects.
Like files, objects contain data -- but unlike files, objects are not organized in a hierarchy. Every object exists at the same level in a flat address space called a storage pool and one object cannot be placed inside another object.
Both files and objects have metadata associated with the data they contain, but objects are characterized by their extended metadata. Each object is assigned a unique identifier which allows a server or end user to retrieve the object without needing to know the physical location of the data. This approach is useful for automating and streamlining data storage in cloud computing environments.
Object storage is often compared to valet parking at an upscale restaurant. When a customer uses valet parking, he exchanges his car keys for a receipt. The customer does not know where his car will be parked or how many times an attendant might move the car while the customer is dining. In this analogy, a storage object's unique identifier represents the customer's receipt. ( Source : http://searchstorage.techtarget.com/definition/object-storage )
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