Re: tlug: CODA distributed filesystem

[Frank Bennett <bennett@example.com>]

Jonathan Byrne - 3Web <jq@example.com> writes:

> >_possibilities_.  :) As I think I mentioned in the last posting
> >on this, CODA supports disconnection, so your laptop can be part
> >of a distributed FS as well.
> 
> This disconnection feature sounds sort of like the Windows 95 briefcase, only
> a whole lot more advanced.  If you have, for example, a desktop machine where
> /home is a CODA FS and you have the same /home on a notebook as a CODA FS,
> does it auto-sync them when you hook the notebook up to the desktop machine?
> If so, can it sync across a TCP/IP connection? This could have interesting
> ramifications for the future of the TLUG library :-)

The physical center of the CODA filesystem (actually a CODA
filesystem volume, I think --- I'm still getting my head around
the language used to describe this) is controlled by a server,
which could be run on the desktop.  The laptop would run a CODA
client, which could select the filespace served by the desktop as
one of its volumes.

The client keeps a cache of files locally, and files in cache are
accessible even if the network abruptly cuts out (or you yank the
cable on your laptop and go home).  You can set priorities for
which files you need most, using a control database, and you can
enforce the priorities on a filesystem at rest by issuing a
special command ("hoard walk", I think).  So the idea is that you
run the command, wait around a bit, then pull the plug and go
home.

When you reconnect, everything should sync up automatically, yes.
If there are conflicts, you should be warned, and there are admin
tools (looks like this is still pretty rough at the
user/administrator end, though) for recovering from conflict
conditions that might result, say, when two people edit the same
file offline.

Access to secure parts of the filesystem is via a key, for which
a user applies and is granted.  Keys are valid for 25 hours,
after which they have to be renewed.

Because you can snatch multiple CODA volumes to a single client,
you can stash as big a filesystem as you like, provided you have
the cache space on the client to run it.

Oh, and yes, this all runs across TCP/IP.  The first test you run
to check the read-only space carries you to the eastern seaboard
of the US, Sweden and probably a few other places.  All one
filesystem.

Cheers,
-- 
-x80
Frank G Bennett, Jr         @@
Faculty of Law, Nagoya Univ () email: bennett@example.com
Tel: +81[(0)52]789-2239     () WWW:   http://rumple.soas.ac.uk/~bennett/

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