6d77c379bd
Prior to this commit, swift-ring-builder would place partitions on devices by first going for maximal dispersion and breaking ties with device weight. This commit flips the order so that device weight trumps dispersion. Note: if your ring can be balanced, you won't see a behavior change. It's only when device weights and maximal-dispersion come into conflict that this commit changes anything. Example: a cluster with two regions. Region 1 has a combined weight of 1000, while region 2 has a combined weight of only 400. The ring has 3 replicas and 2^16 partitions. Prior to this commit, the balance would look like so: Region 1: 2 * 2^16 partitions Region 2: 2^16 partitions After this commit, the balance will be: Region 1: 10/14 * 2^16 partitions (more than before) Region 2: 4/14 * 2^16 partitions (fewer than before) One consequence of this is that some partitions will not have a replica in region 2, since it's not big enough to hold all of them. This way, a cluster operator can add a new region to a single-region cluster in a gradual fashion so as not to destroy their WAN link with replication traffic. As device weights are increased in the second region, more replicas will shift over to it. Once its weight is half that of the first region's, every partition will have a replica there. DocImpact Change-Id: I945abcc4a2917bb12be554b640f7507dd23cd0da |
||
|---|---|---|
| bin | ||
| doc | ||
| etc | ||
| examples | ||
| locale | ||
| swift | ||
| test | ||
| .coveragerc | ||
| .functests | ||
| .gitignore | ||
| .gitreview | ||
| .mailmap | ||
| .probetests | ||
| .unittests | ||
| AUTHORS | ||
| babel.cfg | ||
| CHANGELOG | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| MANIFEST.in | ||
| README.md | ||
| requirements.txt | ||
| setup.cfg | ||
| setup.py | ||
| test-requirements.txt | ||
| tox.ini | ||
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