[tahoe-announce] ANNOUNCING Tahoe-LAFS v1.7N2! Please test!

Zooko O'Whielacronx zookog at gmail.com
Wed Jun 9 08:27:45 PDT 2010


The Tahoe-LAFS volunteer hackers have done a superb job for the last
few weeks, iteratively testing and refining the major new features of
Tahoe-LAFS v1.7.

The current version passes our comprehensive test suite on many
platforms (see the Buildbot [1] especially the "Supported Platforms"

This is officially Tahoe-LAFS v1.7.0N2!

The plan is that this version will become v1.7.0 final except for
improving the documentation and packaging, and fixing any critical
bugs that turn up.

Tahoe-LAFS v1.7 is going to be a major new release, adding important
features and continuing our strong tradition of reliability and


There are three major new features (not counting various small
bugfixes and improvements): SFTP support, support for non-ASCII
character encodings, and Servers of Happiness.

* SFTP support

Your Tahoe-LAFS gateway now acts like a full-fledged SFTP server. It
has been tested with sshfs to provide a virtual filesystem in Linux.
Many users have asked for this feature. We hope that it serves them
well! See the FTP-and-SFTP.txt document [2] to get started.

* support for non-ASCII character encodings

Tahoe-LAFS now correctly handles filenames containing non-ASCII
characters on all supported platforms:

 - when reading files in from the local filesystem (such as when you
run "tahoe backup" to back up your local files to a Tahoe-LAFS grid);
 - when writing files out to the local filesystem (such as when you
run "tahoe cp -r" to recursively copy files out of a Tahoe-LAFS grid);
 - when displaying filenames to the terminal (such as when you run
"tahoe ls"), subject to limitations of the terminal and locale;
 - when parsing command-line arguments, except on Windows (to be fixed
on Windows in a future release)

* Servers of Happiness

Tahoe-LAFS now measures during immutable file upload to see how well
distributed it is across multiple servers. It aborts the upload if the
pieces of the file are not sufficiently well-distributed.

This behavior is controlled by a configuration parameter called
"servers of happiness". With the default settings for its erasure
coding, Tahoe-LAFS generates 10 shares for each file, such that any 3
of those shares are sufficient to recover the file. The default value
of "servers of happiness" is 7, which means that Tahoe-LAFS will
guarantee that there are at least 7 servers holding
some of the shares, such that any 3 of those servers can completely
recover your file.

The new upload code also distributes the shares better than the
previous version in some cases and takes better advantage of
pre-existing shares (when a file has already been previously
uploaded). See the architecture.txt document [3] for details.


Follow the instructions in the quickstart.html document [4].


Do not be too disappointed if you discover the following performance issue.

While this release makes it possible to use Tahoe-LAFS as a mostly
POSIX-compliant filesystem (thanks to FUSE and sshfs), it will have
very bad performance for some cases which have good performance on
your traditional local filesystem. In particular it is bad at making
small changes to large files (it actually stores the new file contents
every time you write to the file and re-uploads the entire file every
time you close it after having written to it). On the other hand it
has some nice scalability and load-balancing characteristics compared
to traditional POSIX filesystemsbyou will be able to easily add tens
or hundreds of computers to your distributed, shared Tahoe-LAFS
filesystem and it will take advantage of them in a nice distributed
pattern without going noticeably slower than if you had a single
Tahoe-LAFS server.

So, you should not assume that the POSIX emulation of Tahoe-LAFS v1.7
will perform sufficiently well at a particular use case or load
pattern until you've tried it, but if you do try it and it does
perform acceptably well then you can feel confident that it will
continue to perform that well as you scale out your filesystem.

Improving the performance in some dimensions is one of the goals of
the Google Summer of Code Project which will result in Tahoe-LAFS v1.8
this Fall (northern hemisphere).


This release continues the tradition of full backward-compatibility.
Use it without fear.


We think Tahoe-LAFS is a really cool hack with great potential. That's
why we spend our time on it as a labor of love. We hope you find good
uses for it.


Zooko, release manager of v1.7

[1] http://tahoe-lafs.org/buildbot/
[2] http://tahoe-lafs.org/trac/tahoe-lafs/browser/docs/frontends/FTP-and-SFTP.txt
[3] http://tahoe-lafs.org/trac/tahoe-lafs/browser/docs/architecture.txt
[4] http://tahoe-lafs.org/source/tahoe-lafs/trunk/docs/quickstart.html
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