tahoe-lafs/docs/NEWS

User visible changes in Tahoe.  -*- outline -*-

* Release 1.1.0 (2008-06-11)

** CLI: new "alias" model

The new CLI code uses an scp/rsync -like interface, in which directories in
the Tahoe storage grid are referenced by a colon-suffixed alias. The new
commands look like:
 tahoe cp local.txt tahoe:virtual.txt
 tahoe ls work:subdir

More functionality is available through the CLI: creating unlinked files and
directories, recursive copy in or out of the storage grid, hardlinks, and
retrieving the raw read- or write- caps through the 'ls' command. Please read
docs/CLI.txt for complete details.

** webapi: new pages, new commands

Several new pages were added to the web API:

 /helper_status : to describe what a Helper is doing
 /statistics : reports node uptime, CPU usage, other stats
 /file : for easy file-download URLs, see #221
 /cap == /uri : future compatibility

The localdir=/localfile= and t=download operations were removed. These
required special configuration to enable anyways, but this feature was a
security problem, and was mostly obviated by the new "cp -r" command.

Several new options to the GET command were added:

 t=deep-size : add up the size of all immutable files reachable from the directory
 t=deep-stats : return a JSON-encoded description of number of files, size
                distribution, total size, etc

POST is now preferred over PUT for most operations which cause side-effects.

Most webapi calls now accept overwrite=, and default to overwrite=true .

"POST /uri/DIRCAP/parent/child?t=mkdir" is now the preferred API to create
multiple directories at once, rather than ...?t=mkdir-p .

PUT to a mutable file ("PUT /uri/MUTABLEFILECAP", "PUT /uri/DIRCAP/child")
will modify the file in-place.

** more munin graphs in misc/munin/

  tahoe-introstats
  tahoe-rootdir-space
  tahoe_estimate_files
  mutable files published/retrieved
  tahoe_cpu_watcher
  tahoe_spacetime

** New Dependencies

  zfec 1.1.0
  foolscap 0.2.8
  pycryptopp 0.5
  setuptools (now required at runtime)

** New Mutable-File Code

The mutable-file handling code (mostly used for directories) has been
completely rewritten. The new scheme has a better API (with a modify()
method) and is less likely to lose data when several uncoordinated writers
change a file at the same time.

In addition, a single Tahoe process will coordinate its own writes. If you
make two concurrent directory-modifying webapi calls to a single tahoe node,
it will internally make one of them wait for the other to complete. This
prevents auto-collision (#391).

The new mutable-file code also detects errors during publish better. Earlier
releases might believe that a mutable file was published when in fact it
failed.

** other features

The node now monitors its own CPU usage, as a percentage, measured every 60
seconds. 1/5/15 minute moving averages are available on the /statistics web
page and via the stats-gathering interface.

Clients now accelerate reconnection to all servers after being offline
(#374). When a client is offline for a long time, it scales back reconnection
attempts to approximately once per hour, so it may take a while to make the
first attempt, but once any attempt succeeds, the other server connections
will be retried immediately.

A new "offloaded KeyGenerator" facility can be configured, to move RSA key
generation out from, say, a webapi node, into a separate process. RSA keys
can take several seconds to create, and so a webapi node which is being used
for directory creation will be unavailable for anything else during this
time. The Key Generator process will pre-compute a small pool of keys, to
speed things up further. This also takes better advantage of multi-core CPUs,
or SMP hosts.

The node will only use a potentially-slow "du -s" command at startup (to
measure how much space has been used) if the "sizelimit" parameter has been
configured (to limit how much space is used). Large storage servers should
turn off sizelimit until a later release improves the space-management code,
since "du -s" on a terabyte filesystem can take hours.

The Introducer now allows new announcements to replace old ones, to avoid
buildups of obsolete announcements.

Immutable files are limited to about 12GiB (when using the default 3-of-10
encoding), because larger files would be corrupted by the four-byte
share-size field on the storage servers (#439). A later release will remove
this limit. Earlier releases would allow >12GiB uploads, but the resulting
file would be unretrievable.

The docs/ directory has been rearranged, with old docs put in
docs/historical/ and not-yet-implemented ones in docs/proposed/ .

The Mac OS-X FUSE plugin has a significant bug fix: earlier versions would
corrupt writes that used seek() instead of writing the file in linear order.
The rsync tool is known to perform writes in this order. This has been fixed.