update the README file

changing the README file to clarify swift-on-file operations
and update with latest code changes

Signed-off-by: Thiago da Silva <thiago@redhat.com>
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Thiago da Silva 2014-08-28 14:01:37 -04:00
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# Swift-on-File
Swift-on-File, formerly called Gluster-Swift, is a Swift Object Server
implementation that enables objects created using the Swift API to be accessed
as files on a Posix filesystem.
Swift-on-File is a Swift Object Server implementation that enables users to
access the same data, both as an object and as a file. Data can be stored and
retrieved through Swift's REST interface or as files from NAS interfaces
including native GlusterFS, NFS and CIFS.
Swift-on-File is to be deployed as a Swift [storage policy](http://docs.openstack.org/developer/swift/overview_policies.html),
which provides the advantages of being able to extend an existing Swift cluster
and also migrating data to and from policies with different storage backends.
The main difference from the default Swift Object Server is that Swift-on-File
stores objects following the same path hierarchy as that object's URL.
On a vanilla openstack swift the object server will store the object following
the mapping given by the Ring and its final storage location and filename are
unknown to the user. In the case of Sof, the object will be stored in the
configured filesystem volume with the same directory structure as the object's
URL.
stores objects following the same path hierarchy as the object's URL. In contrast,
the default Swift implementation stores the object following the mapping given
by the Ring, and its final file path is unkown to the user.
For example, an object with URL: https://swift.example.com/v1/acc/cont/obj,
would be stored in the following way:
* Swift: /mnt/sdb1/2/node/sdb2/objects/981/f79/f566bd022b9285b05e665fd7b843bf79/1401254393.89313.data
* SoF: /mnt/gluster-vol/acc/cont/obj
For example, an object with URL: `https://swift.example.com/v1/acct/cont/obj`,
would be stored the following way by the two systems:
* Swift: `/mnt/sdb1/2/node/sdb2/objects/981/f79/f566bd022b9285b05e665fd7b843bf79/1401254393.89313.data`
* SoF: `/mnt/swiftonfile/acct/cont/obj`
## Roadmap
Swift-On-File is in a transition period. The project was recently renamed from
Gluster-Swift to Swift-on-File to better represent its nature of a Swift backend
that supports multiple Posix Filesystems, not just GlusterFS. It is also
transitioning to become a Swift Storage Policy. While Gluster-Swift had to be
deployed as its own cluster, SoF can be deployed as a storage policy on an
existing Swift cluster. This is a tremendous change to the project as it opens
up new possibilities of how SoF can be used, such as, enabling the ability to
consume and migrate existing file storage (e.g., NFS) on a swift cluster.
## Use cases
Swift-on-File can be especially useful in cases where access over multiple
protocols is desired. For example, imagine a deployment where video files
are uploaded as objects over Swift's REST interface and a legacy video transcoding
software access those videos as files.
Our last stable [release](https://github.com/swiftonfile/swiftonfile/releases)
was targetting the Swift Icehouse release. This was the last release of
Gluster-Swift. The next release will target Juno, with support for storage
policies.
Another use case is where users might need to migrate data from an existing file
storage systems to a Swift cluster.
Besides the work to support Storage Policies we also plan on adding support
for other Filesystems (e.g., NFS) and also for enabling the access of objects
through multiple protocols.
## Limitations and Future plans
Swift-On-File currently works only with Filesystems with extended attributes
support. It is also recommended that these Filesystems provide data durability
as Swift-On-File should not use Swift's replication mechanisms.
GlusterFS is a good example of a Filesystem that works well with Swift-on-File,
GlusterFS provides a posix interface, global namespace, scalability, data
replication and support for extended attributes.
Currently, files added over a NAS protocol (e.g., native GlusterFS), do not show
up in container listings, still those files would be accessible over Swift's REST
interface with a GET request. We are working to provide a solution to this limitation.
Future plans includes adding support for Filesystems without extended attributes,
which should extend the ability to migrate data for legacy storage systems.
To learn more about the history of Gluster-Swift and how Swift-On-File came
to be, you can watch this presentation given at the Atlanta Openstack Summit:
[Breaking the Mold with Openstack Swift and GlusterFS](http://youtu.be/pSWdzjA8WuA).
## Get involved:
To learn more about Swift-On-File, you can watch this presentation given at
the Atlanta Openstack Summit: [Breaking the Mold with Openstack Swift and GlusterFS](http://youtu.be/pSWdzjA8WuA).
Presentation slides can be found [here](http://lpabon.github.io/openstack-summit-2014).
## Supported Filesystems:
* XFS
* GlusterFS
## Get involved:
Join us in contributing to the project. Feel free to file bugs, help with documentation
or work directly on the code. You can communicate with us using GitHub [issues](https://github.com/swiftonfile/swiftonfile/issues) or find
us in the #swiftonfile channel on Freenode.
@ -54,4 +57,3 @@ us in the #swiftonfile channel on Freenode.
# Guides to get started:
1. [Quick Start Guide with XFS/GlusterFS](doc/markdown/quick_start_guide.md)
1. [Developer Guide](doc/markdown/dev_guide.md)