68db481ae5
The replica placement algorithm works on regions, then zones, then IP/port, then device ID. The handoff algorithm worked on regions, then zones, then device ID, completely skipping IP/port. It's now been updated to take IP/port into consideration. This means you get one handoff on each machine in the cluster before you start getting handoffs that share a machine with a previous one. In small clusters, this can help with durability. Because this is performance-critical code, here are some quick benchmark results: Run time averages over 25000 trials on a 1200-device ring (20 part power, 3 replicas, 2 regions, 10 zones, 120 nodes): | master | branch ===================+=============+============ get 1 more node | 2.727e-05 | 3.076e-05 get 6 more nodes | 3.55e-05 | 4.214e-05 get all more nodes | 0.002247 | 0.002691 There's a small slowdown from the additional bookkeeping, but nothing too awful. The time to get 6 more nodes (for handoff checks on 404, it's 2x replica count by default, hence 6) went from 35 to 42 microseconds, so it remains small. Change-Id: Ie7da4dfcb0fcf1a38e2fb13f60c204540fadbf06
Swift
A distributed object storage system designed to scale from a single machine to thousands of servers. Swift is optimized for multi-tenancy and high concurrency. Swift is ideal for backups, web and mobile content, and any other unstructured data that can grow without bound.
Swift provides a simple, REST-based API fully documented at http://docs.openstack.org/.
Swift was originally developed as the basis for Rackspace's Cloud Files and was open-sourced in 2010 as part of the OpenStack project. It has since grown to include contributions from many companies and has spawned a thriving ecosystem of 3rd party tools. Swift's contributors are listed in the AUTHORS file.
Docs
To build documentation install sphinx (pip install sphinx), run
python setup.py build_sphinx, and then browse to /doc/build/html/index.html.
These docs are auto-generated after every commit and available online at
http://docs.openstack.org/developer/swift/.
For Developers
The best place to get started is the "SAIO - Swift All In One". This document will walk you through setting up a development cluster of Swift in a VM. The SAIO environment is ideal for running small-scale tests against swift and trying out new features and bug fixes.
You can run unit tests with .unittests and functional tests with
.functests.
Code Organization
- bin/: Executable scripts that are the processes run by the deployer
- doc/: Documentation
- etc/: Sample config files
- swift/: Core code
- account/: account server
- common/: code shared by different modules
- middleware/: "standard", officially-supported middleware
- ring/: code implementing Swift's ring
- container/: container server
- obj/: object server
- proxy/: proxy server
- test/: Unit and functional tests
Data Flow
Swift is a WSGI application and uses eventlet's WSGI server. After the
processes are running, the entry point for new requests is the Application
class in swift/proxy/server.py. From there, a controller is chosen, and the
request is processed. The proxy may choose to forward the request to a back-
end server. For example, the entry point for requests to the object server is
the ObjectController class in swift/obj/server.py.
For Deployers
Deployer docs are also available at http://docs.openstack.org/developer/swift/. A good starting point is at http://docs.openstack.org/developer/swift/deployment_guide.html
You can run functional tests against a swift cluster with .functests. These
functional tests require /etc/swift/test.conf to run. A sample config file
can be found in this source tree in test/sample.conf.
For Client Apps
For client applications, official Python language bindings are provided at http://github.com/openstack/python-swiftclient.
Complete API documentation at http://docs.openstack.org/api/openstack-object-storage/1.0/content/
For more information come hang out in #openstack-swift on freenode.
Thanks,
The Swift Development Team