OpenStack Storage (Swift)
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Samuel Merritt d9f2a76973 Local write affinity for object PUT requests.
The proxy can now be configured to prefer local object servers for PUT
requests, where "local" is governed by the "write_affinity". The
"write_affinity_node_count" setting controls how many local object
servers to try before giving up and going on to remote ones.

I chose to simply re-order the object servers instead of filtering out
nonlocal ones so that, if all of the local ones are down, clients can
still get successful responses (just slower).

The goal is to trade availability for throughput. By writing to local
object servers across fast LAN links, clients get better throughput
than if the object servers were far away over slow WAN links. The
downside, of course, is that data availability (not durability) may
suffer when drives fail.

The default configuration has no write affinity in it, so the default
behavior is unchanged.

Added some words about these settings to the admin guide.

DocImpact

Change-Id: I09a0bd00524544ff627a3bccdcdc48f40720a86e
2013-06-23 22:04:56 -07:00
bin Merge "Add "normal", optparse-style options to swift-ring-builder add." 2013-06-21 15:22:51 +00:00
doc Local write affinity for object PUT requests. 2013-06-23 22:04:56 -07:00
etc Local write affinity for object PUT requests. 2013-06-23 22:04:56 -07:00
examples Add example Apache config files 2013-06-20 21:56:21 +03:00
locale Reverted the pulling out of various middleware: 2012-05-16 21:25:10 +00:00
swift Local write affinity for object PUT requests. 2013-06-23 22:04:56 -07:00
test Local write affinity for object PUT requests. 2013-06-23 22:04:56 -07:00
.coveragerc Align tox.ini and fix coverage jobs in jenkins. 2012-06-08 20:05:14 -04:00
.functests Allow dot test runners from any dir 2012-12-07 14:08:49 -08:00
.gitignore update .gitignore 2013-06-20 17:58:50 +08:00
.gitreview Add .gitreview config file for gerrit. 2011-10-24 15:05:49 -04:00
.mailmap copy X-Delete-At unless X-Fresh-Metadata: true is supplied on an object copy 2013-04-24 10:40:41 -04:00
.probetests Allow dot test runners from any dir 2012-12-07 14:08:49 -08:00
.unittests Add branch coverage reporting 2013-06-10 10:30:40 -04:00
AUTHORS fix email address 2013-04-11 10:42:31 -07:00
babel.cfg add pybabel setup.py commands and initial .pot 2011-01-27 00:01:24 +00:00
CHANGELOG updated AUTHORS and CHANGELOG 2013-03-28 21:01:49 -07:00
CONTRIBUTING.md Add CONTRIBUTING file. 2012-11-21 11:23:15 -08:00
LICENSE Convert LICENSE to use unix style line endings. 2012-12-19 12:48:27 -05:00
MANIFEST.in Add requirements files to the source distribution 2013-06-03 19:26:20 +04:00
README.md new more helpful README 2012-09-13 20:59:41 -07:00
requirements.txt Rename requires files to standard names. 2013-05-30 22:14:01 +00:00
setup.cfg Change setup.cfg style. 2013-04-02 15:55:56 +04:00
setup.py Rename requires files to standard names. 2013-05-30 22:14:01 +00:00
test-requirements.txt Rename requires files to standard names. 2013-05-30 22:14:01 +00:00
tox.ini Merge "python3: Introduce py33 to tox.ini" 2013-06-21 01:45:45 +00:00

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://doc.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