Swift 2.4.0 release

From: http://lists.openstack.org/pipermail/openstack-announce/2015-September/000575.html

I'm pleased to announce that Swift 2.4.0 is available. As always, you can upgrade to

this version with no end-user downtime. This release has several very nice features,
so I recommend that you upgrade as soon as possible.

You can find the release at:
     https://launchpad.net/swift/liberty/2.4.0

Please note the dependency and config changes in the full release notes:
     https://github.com/openstack/swift/blob/master/CHANGELOG

This release is the result of 55 code contributors, including 29 first-time code
contributors. These are the first-time code contributors:

Timur Alperovich           Kazuhiro Miyahara
Minwoo Bae                 Takashi Natsume
Tim Burke                  Ondrej Novy
Carlos Cavanna             Falk Reimann
Emmanuel Cazenave          Brian Reitz
Clément Contini            Eran Rom
Oshrit Feder               Hamdi Roumani
Charles Hsu                Atsushi Sakai
Joanna H. Huang            Azhagu Selvan SP
Bill Huber                 Alexandra Settle
Jaivish Kothari            Pradeep Kumar Singh
Zhao Lei                   Victor Stinner
Ben Martin                 Akihito Takai
Kenichiro Matsuda          Kai Zhang
Michael Matur


I'd like to call out a few significant changes in this release. Please read
the release notes in the link above for more information about these new
features.

* Allow one or more object servers per disk deployment

  This new deployment model allows you to set the number of object servers per
  drive. The basic change is that you add every drive into the ring at a
  different port, and Swift will automatically run the configured number of
  server processes for each drive. This results in per-disk isolated IO so
  that one slow disk does not slow down every operation to that server. This
  change can dramatically lower request latency and increase requests per
  second.

* Improve performance for object writes to large containers

  When an object is written in Swift, the object servers will attempt to
  update the listing in the appropriate container server before giving a
  response to the client. If the container server is busy, object latency
  increases as the object server waits for the container server. In this
  release, the object server waits less time (and the wait time is
  configurable) for the container server response, thus lowering overall
  latency. Effectively, this means that object writes will no longer get
  slower as the number of objects in a container increases.

* Users can set per-object metadata with bulk upload

  Bulk uploads allow users to upload an archive (.tar) to Swift and store the
  individual referenced files as separate objects in the system. Swift now
  observes extended attributes set on these files and appropriately sets user
  metadata on the stored objects.

* Allow SLO PUTs to forgo per-segment integrity checks.

  Previously, each segment referenced in the manifest also needed the correct
  etag and bytes setting. These fields now allow the "null" value to skip
  those particular checks on the given segment.

There are many other changes that have gone into this release. I encourage you to review
the release notes and upgrade to this release.

Thank you to everyone who contributed to this release. If you would like to get involved
in Swift, please join us in #openstack-swift on freenode IRC.