7f636a5572
The addition of range support for SLO segments (commit 25d5e68) required the range size to be at least the SLO minimum segment size (default 1 MiB). However, if you're doing something like assembling a video of short clips out of a larger one, then you might not need a full 1 MiB. The reason for the 1 MiB restriction was to protect Swift from resource overconsumption. It takes CPU, RAM, and internal bandwidth to connect to an object server, so it's much cheaper to serve a 10 GiB SLO if it has 10 MiB segments than if it has 10 B segments. Instead of a strict limit, now we apply ratelimiting to small segments. The threshold for "small" is configurable and defaults to 1 MiB. SLO segments may now be as small as 1 byte. If a client makes SLOs as before, it'll still be able to download the objects as fast as Swift can serve them. However, a SLO with a lot of small ranges or segments will be slowed down to avoid resource overconsumption. This is similar to how DLOs work, except that DLOs ratelimit *every* segment, not just small ones. UpgradeImpact For operators: if your cluster has enabled ratelimiting for SLO, you will want to set rate_limit_under_size to a large number prior to upgrade. This will preserve your existing behavior of ratelimiting all SLO segments. 5368709123 is a good value, as that's 1 greater than the default max object size. Alternately, hold down the 9 key until you get bored. If your cluster has not enabled ratelimiting for SLO (the default), no action is needed. Change-Id: Id1ff7742308ed816038a5c44ec548afa26612b95
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.
If you would like to start contributing, check out these notes to help you get started.
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