3bdd01cf4a
If a previous partition power increase failed to cleanup all files in
their old partition locations, then during the next partition power
increase the relinker may find the same file to relink in more than
one source partition. This currently leads to an error log due to the
second relink attempt getting an EEXIST error.
With this patch, when an EEXIST is raised, the relinker will attempt
to create/verify a link from older partition power locations to the
next part power location, and if such a link is found then suppress
the error log.
During the relink step, if an alternative link is verified and if a
file is found that is neither linked to the next partition power
location nor in the current part power location, then the file is
removed during the relink step. That prevents the same EEXIST occuring
again during the cleanup step when it may no longer be possible to
verify that an alternative link exists.
For example, consider identical filenames in the N+1th, Nth and N-1th
partition power locations, with the N+1th being linked to the Nth:
- During relink, the Nth location is visited and its link is
verified. Then the N-1th location is visited and an EEXIST error
is encountered, but the new check verifies that a link exists to
the Nth location, which is OK.
- During cleanup the locations are visited in the same order, but
files are removed so that the Nth location file no longer exists
when the N-1th location is visited. If the N-1th location still
has a conflicting file then existence of an alternative link to
the Nth location can no longer be verified, so an error would be
raised. Therefore, the N-1th location file must be removed during
relink.
The error is only suppressed for tombstones. The number of partition
power location that the relinker will look back over may be configured
using the link_check_limit option in a conf file or --link-check-limit
on the command line, and defaults to 2.
Closes-Bug: 1921718
Change-Id: If9beb9efabdad64e81d92708f862146d5fafb16c
OpenStack Swift
OpenStack Swift is 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 https://docs.openstack.org/swift/latest/.
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 run:
pip install -r requirements.txt -r doc/requirements.txt
sphinx-build -W -b html doc/source doc/build/htmland then browse to doc/build/html/index.html. These docs are auto-generated after every commit and available online at https://docs.openstack.org/swift/latest/.
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.
To fully run the tests, the target environment must use a filesystem
that supports large xattrs. XFS is strongly recommended. For unit tests
and in-process functional tests, either mount /tmp with XFS
or provide another XFS filesystem via the TMPDIR
environment variable. Without this setting, tests should still pass, but
a very large number will be skipped.
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 https://docs.openstack.org/swift/latest/. A good starting point is at https://docs.openstack.org/swift/latest/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 https://github.com/openstack/python-swiftclient.
Complete API documentation at https://docs.openstack.org/api-ref/object-store/
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