mirror of
https://github.com/tahoe-lafs/tahoe-lafs.git
synced 2024-12-19 04:57:54 +00:00
106 lines
4.5 KiB
Plaintext
106 lines
4.5 KiB
Plaintext
Allmydata, Inc. [1], provider of the "Allmydata" consumer backup product, is
|
|
pleased announce the first public release of "Tahoe", an open source
|
|
decentralized storage mesh.
|
|
|
|
The source code that we are releasing is the current working prototype for
|
|
Allmydata's next-generation product. This prototype is not recommended for
|
|
storage of confidential data nor for data which is not otherwise backed up,
|
|
but it is already implements a functional decentralized storage mesh and is
|
|
useful for experimentation, prototyping, and extension.
|
|
|
|
|
|
Installation
|
|
|
|
This release of Tahoe is guaranteed to work only on Linux. It may actually
|
|
work on other platforms -- earlier development revisions have been used on
|
|
Windows, Cygwin, Mac/Intel, and Mac/PPC -- but not all of the unit tests
|
|
currently pass on all platforms (see "Hacking and Community", below), so
|
|
we're officially proclaiming that it works on Linux.
|
|
|
|
To install, download the tarball [2], untar it, cd into the resulting
|
|
directory, and follow the directions in the README [3].
|
|
|
|
|
|
Usage
|
|
|
|
XYZ Brian: please insert intro to UI
|
|
|
|
|
|
Hacking and Community
|
|
|
|
Please join the mailing list [4] and to discuss the ideas behind Tahoe and
|
|
extensions of and uses of Tahoe. Patches that extend and improve Tahoe are
|
|
gratefully accepted -- roadmap.txt [5] shows the next improvements that we
|
|
plan to make. You can browse the revision control history, source code, and
|
|
issue tracking at the Trac instance [6]. Please note the buildbot results
|
|
page [7], which show how Tahoe builds and passes unit tests on each checkin,
|
|
and the code coverage results [8] and percentage-covered graph [9], which
|
|
show how much of the Tahoe source code is currently exercised the test suite.
|
|
|
|
|
|
Licence
|
|
|
|
Tahoe is offered under the GNU General Public License (v2). It also comes
|
|
with the added permission that, in the case that you are obligated to release
|
|
a derived work under this licence (as per section 2.b of the GPLv2), you may
|
|
delay the fulfillment of this obligation for up to 12 months.
|
|
|
|
|
|
Network Architecture
|
|
|
|
Each peer maintains a connection to each other peer. A single distinct
|
|
server called an "introducer" is used to discover other peers with which to
|
|
connect.
|
|
|
|
To store a file, the file is encrypted and erasure coded, and each resulting
|
|
share is uploaded to a different peer. The secure hash of the encrypted file
|
|
and the encryption key are packed into a URI, knowledge of which is necessary
|
|
and sufficient to recover the file.
|
|
|
|
To fetch a file, starting with the URI, a subset of shares is downloaded from
|
|
peers, the file is reconstructed from the shares, and then decrypted.
|
|
|
|
A single distinct server called a "vdrive server" maintains a mapping from
|
|
pathnames/filenames to URIs.
|
|
|
|
We are well aware of the limitations of decentralization and scalability
|
|
inherent in this prototype. In particular, the completely-connected property
|
|
of the mesh and the requirement of a single distinct introducer and vdrive
|
|
server limits the possible size of the mesh. We have plans to loosen these
|
|
limitations (see roadmap.txt [5]). Currently it should be noted that the
|
|
mesh already depends as little as possible on the accessibility and
|
|
correctness of the introduction server and the vdrive server, and the choice
|
|
of which servers to use is easily configured.
|
|
|
|
|
|
Software Architecture
|
|
|
|
Tahoe is a "from the ground-up" rewrite, inspired by Allmydata's existing
|
|
consumer backup service, written in Python.
|
|
|
|
It uses the Foolscap library [10] which provides a remote object protocol
|
|
inspired by the capability-secure "E" programming language [11]. Foolscap
|
|
allows us to express the intended behavior of the distributed mesh directly
|
|
in object-oriented terms while relying on a well-engineered, secure transport
|
|
layer.
|
|
|
|
The underlying networking is provided by the Twisted library [12].
|
|
Computationally intensive operations are performed in native compiled code,
|
|
such as the "zfec" library for fast erasure coding (also available
|
|
separately: [13]).
|
|
|
|
|
|
[1] http://allmydata.com
|
|
[2] http://allmydata.com/source/tahoe-0.1.0-0-UNSTABLE.tar.bz2
|
|
[3] http://allmydata.com/source/tahoe/README
|
|
[4] https://postman.allmydata.com/cgi-bin/mailman/listinfo/tahoe XYZ Zandr or someone: right URL?
|
|
[5] http://allmydata.com/source/tahoe/roadmap.txt
|
|
[6] http://allmydata.org/trac XYZ Brian: right URL?
|
|
[7] http://allmydata.org/buildbot XYZ Brian: right URL?
|
|
[8] http://allmydata.org/code coverage thingie XYZ Brian: right URL?
|
|
[9] http://allmydata.org/munin XYZ Brian: right URL?
|
|
[10] http://twistedmatrix.com/trac/wiki/FoolsCap
|
|
[11] http://erights.org/
|
|
[12] http://twistedmatrix.com/
|
|
[13] http://allmydata.com/source/zfec
|