b4ee36ef11
SOF can support object names of upto 1024 if it conforms to the
following constraints:
Object names can have forward slashes ('/') in them. Each segment in
between these slashes cannot exceed 255 characters with exception of
the last segment which cannot exceed 221 characters.
This constraint arises from the fact that each segment except the last
one in object name is a directory, the last segment being an actual
file on the filesystem.
Also, restored default constraint values in swift.conf since the SOF
constraints middleware (always in proxy pipeline) will take care of it.
Change-Id: Ia7dc44671a87911c092fecd0344eace92f5c225b
Signed-off-by: Prashanth Pai <ppai@redhat.com>
Swift-on-File
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, 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 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/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
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.
Another use case is where users might need to migrate data from an existing file storage systems to a Swift cluster.
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.
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. Presentation slides can be found here.
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 or find us in the #swiftonfile channel on Freenode.