OpenStack Swift

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　　From: http://searchcloudstorage.techtarget.com/definition/OpenStack-Swift
　　OpenStack Swift, also known as OpenStack Object Storage, is an open source object storage system that is licensed under the Apache 2.0 license and runs on standard server hardware. OpenStack Swift is best suited to backup and archive unstructured data, such as documents, images, audio and video files, email and virtual machine images.
　　Objects and files are written to multiple drives, and the Swift software ensures the data is replicated across a server cluster. By default, Swift places three copies of every object in as unique-as-possible locations -- first by region, then by zone, server and drive. If a server or hard drive fails, OpenStack Object Storage replicates its content from active nodes to new locations in the cluster.
　　The system, which is accessed through a REST HTTP application programming interface (API), can scale horizontally to store petabytes of data through the addition of nodes, which typically equate to servers. OpenStack Swift software is based on Cloud Files technology developed by Rackspace Hosting Inc. Rackspace and NASA initiated the project and co-founded the community that develops and maintains OpenStack software, which includes compute, storage and networking components for building cloud computing services.
　　Here is an article to introduce the relationships among SDN, OpenFlow and OpenStack Quantum: http://wikibon.org/wiki/v/SDN,_OpenFlow_and_OpenStack_Quantum
　　Software defined networking (SDN) is a model for network control, based on the idea that network traffic flow can be made programmable at scale, thus enabling new dynamic models for traffic management.
　　
OpenFlow
　　OpenFlow, an "open" protocol to control the traffic flows of multiple switches from a centralized controller, is an example of SDN. The OpenFlow initiative is led by the Open Networking Foundation and the ONF’s founding members are exclusively service providers including Yahoo, Google and Verizon. OpenFlow 1.1 specification is available, although networking vendors are currently using the 1.0 specification (find both specs here).
　　
OpenStack Quantum
　　OpenStack, an open source software initiative for building clouds, has a network connectivity project named Quantum (see project page here). The Quantum project looks to provide "network connectivity as a service" between interface devices (e.g., vNICs) managed by other OpenStack services. Quantum was originally proposed in April 2011 and in less than six months the v1.0 API was made available; it is described as a “young project”, and documentation is a work-in-progress.
　　UPDATE: The OpenStack Quantum project has been renamed Neutron.
　　
How does OpenFlow relate to Quantum?
　　Quantum is an application-level abstraction of networking that relies on plug-in implementations to map the abstraction(s) to reality. OpenFlow-based networking systems are one possible mechanism to be used by a plug-in to deliver a Quantum abstraction.
　　OpenFlow itself does not provide a network abstraction; that takes software that implements the protocol. Quantum itself does not talk to switches directly; that takes additional software (in the form of a plug-in). Those software components may be one and the same, or a Quantum plug-in might talk to OpenFlow-based controller software via an API (like the Open vSwitch API).