da557011ec
The handoffs_first mode in the replicator has the useful behavior of processing all handoff parts across all disks until there aren't any handoffs anymore on the node [1] and then it seemingly tries to drop back into normal operation. In practice I've only ever heard of handoffs_first used while rebalancing and turned off as soon as the rebalance finishes - it's not recommended to run with handoffs_first mode turned on and it emits a warning on startup if option is enabled. The handoffs_first mode on the reconstructor doesn't work - it was prioritizing handoffs *per-part* [2] - which is really unfortunate because in the reconstructor during a rebalance it's often *much* more attractive from an efficiency disk/network perspective to revert a partition from a handoff than it is to rebuild an entire partition from another primary using the other EC fragments in the cluster. This change deprecates handoffs_first in favor of handoffs_only in the reconstructor which is far more useful - and just like handoffs_first mode in the replicator - it gives the operator the option of forcing the consistency engine to focus on rebalance. The handoffs_only behavior is somewhat consistent with the replicator's handoffs_first option (any error on any handoff in the replicactor will make it essentially handoff only forever) but the option does what you want and is named correctly in the reconstructor. For consistency with the replicator the reconstructor will mostly honor the handoffs_first option, but if you set handoffs_only in the config it always takes precedence. Having handoffs_first in your config always results in a warning, but if handoff_only is not set and handoffs_first is true the reconstructor will assume you need handoffs_only and behaves as such. When running in handoffs_only mode the reconstructor will start to log a warning every cycle if you leave it running in handoffs_only after it finishes reverting handoffs. However you should be monitoring on-disk partitions and disable the option as soon as the cluster finishes the full rebalance cycle. 1. Ia324728d42c606e2f9e7d29b4ab5fcbff6e47aea fixed replicator handoffs_first "mode" 2. Unlike replication each partition in a EC policy can have a different kind of job per frag_index, but the cardinality of jobs is typically only one (either sync or revert) unless there's been a bunch of errors during write and then handoffs partitions maybe hold a number of different fragments. Known-Issues: handoffs_only is not documented outside of the example config, see lp bug #1626290 Closes-Bug: #1653018 Change-Id: Idde4b6cf92fab6c45f2c0c2733277701eb436898 |
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| api-ref/source | ||
| bin | ||
| doc | ||
| etc | ||
| examples | ||
| install-guide/source | ||
| releasenotes | ||
| swift | ||
| test | ||
| .alltests | ||
| .coveragerc | ||
| .functests | ||
| .gitignore | ||
| .gitreview | ||
| .mailmap | ||
| .manpages | ||
| .probetests | ||
| .testr.conf | ||
| .unittests | ||
| AUTHORS | ||
| babel.cfg | ||
| bandit.yaml | ||
| bindep.txt | ||
| CHANGELOG | ||
| CONTRIBUTING.rst | ||
| LICENSE | ||
| MANIFEST.in | ||
| README.rst | ||
| requirements.txt | ||
| REVIEW_GUIDELINES.rst | ||
| setup.cfg | ||
| setup.py | ||
| test-requirements.txt | ||
| tox.ini | ||
Team and repository tags
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
Getting Started
Swift is part of OpenStack and follows the code contribution, review, and testing processes common to all OpenStack projects.
If you would like to start contributing, check out these notes to help you get started.
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.
Tests
There are three types of tests included in Swift's source tree.
- Unit tests
- Functional tests
- Probe tests
Unit tests check that small sections of the code behave properly. For example, a unit test may test a single function to ensure that various input gives the expected output. This validates that the code is correct and regressions are not introduced.
Functional tests check that the client API is working as expected. These can be run against any endpoint claiming to support the Swift API (although some tests require multiple accounts with different privilege levels). These are "black box" tests that ensure that client apps written against Swift will continue to work.
Probe tests are "white box" tests that validate the internal workings of a Swift cluster. They are written to work against the "SAIO - Swift All In One" dev environment. For example, a probe test may create an object, delete one replica, and ensure that the background consistency processes find and correct the error.
You can run unit tests with .unittests, functional tests
with .functests, and probe tests with
.probetests. There is an additional .alltests
script that wraps the other three.
Code Organization
- bin/: Executable scripts that are the processes run by the deployer
- doc/: Documentation
- etc/: Sample config files
- examples/: Config snippets used in the docs
- swift/: Core code
- account/: account server
- cli/: code that backs some of the CLI tools in bin/
- common/: code shared by different modules
- middleware/: "standard", officially-supported middleware
- ring/: code implementing Swift's ring
- container/: container server
- locale/: internationalization (translation) data
- obj/: object server
- proxy/: proxy server
- test/: Unit, functional, and probe 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
There is an ops runbook that gives information about how to diagnose and troubleshoot common issues when running a Swift cluster.
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/
There is a large ecosystem of applications and libraries that support and work with OpenStack Swift. Several are listed on the associated projects page.
For more information come hang out in #openstack-swift on freenode.
Thanks,
The Swift Development Team