Coda File System

New work on Coda for Summer 2011

From: Phil Nelson <>
Date: Thu, 16 Jun 2011 11:06:01 -0700
Hello everyone!

    The Coda project is not dead.   The following is the plan for
Coda work for the summer of 2011.



The plan for building a "Coda Appliance" for VirtualBox Summer 2011


   Coda for Windows has stalled due to changes in the kernel module
FSDK.   Coda on windows is using a very old version of FSDK due to
a change in FSDK that would require a rewrite of the Coda kernel module.
While this could be done, it would take quite a bit of time to re-work
the kernel module and go through the normal development cycle.   Windows
has now had the Vista and the Windows 7 release for which the Coda
kernel module does not support.   FSDK does support them, but only
with newer versions that don't work with the Coda code.

   With the development of virtual machines and how well they run on
current hardware, the idea of producing a "Coda Appliance" for a
virtual machine has the following advantages:
    1)  The Appliance can run Linux, the primary platform for Coda
    2)  Other platforms can install the virtual-machine application
        and then run the Coda Appliance getting access to /coda on
        the appliance by normal remote mounting technologies, CIFS
	on Windows or NFS in others.
    3)  It requires no changes to any kernel modules for support of
        all Windows platforms.
    4)  It allows support of other platforms, like Mac OS X or Solaris
        by choosing the a virtual machine platform that works on
        those platforms.
    5)  New releases of Coda can be quickly produce a new appliance
        so updates can be as simple as replacing your appliance.

The Project:

     During the summer of 2011 we will be building a Coda Appliance.
Initial plans are to make sure it works well on Windows XP and 
Windows 7.   Due to the availability of hardware, we will also make
sure it works well on OS X.  We are looking for suggestions and comments
from the Coda community on this project and how to make it better meet
the needs of the Coda users.

 The VM outline:

     1)  We plan on using VirtualBox due to the number of platforms
on which it runs and the fact that is an open source project like Coda.

     2)  We will build a virtual machine that has Coda preinstalled
and has samba exporting /coda read/write over CIFS.

     3)  The VM will be set up with two network interfaces, one a NAT
interface so the VM can talk to Coda servers and a local host only
interface for the export of /coda over CIFS.  This implies that the
host machine is a "one user" machine.

     4)  The appliance will have a desktop on the console for the normal 
to Coda control and monitoring functions like clog, cfs, codacon, repair and
so forth.

     5)  The plan is to have the appliance be a reduced Linux installation
so the entire distribution and Coda cache can fit into an appliance taking
between 200 and 500 Mb.  (For reference, the current Debian installations
require 2.4G of space to install.)

Current State:

    We have already done a "proof of concept" using VirtualBox, with
Debian installed in the VM image and hosted on an a Mac OS X machine.
This initial appliance is a standard Debian, 4G installation without
much customization.  It is currently available for a short time at  It will soon be available by torrent.
Information on the torrent will be sent to this list.  To use this, you
need virtualbox ( installed, get the Coda.ova and import
this appliance via the "file" menu.
(MD5 (Coda.ova) = 4a3b1d3e0c3e19355dd5e8096e99df55)

    It should just work out of the box on OS X.  Finder should find a
"coda" machine and there should be a coda volume.  You should connect
as user guest with password guest. All passwords are set to guest on
this appliance.   For Windows XP, you will need to reset the ethernet
adaptor 2 to a "host only" adapter before you run the VM.  You can
them map the network resource \\coda\coda using guest/guest as described
above.   The workgroup is "WORKGROUP" and can be changed in the samba
configuration file /etc/samba/smb.conf.   This allows XP to see the
coda appliance when looking at your workgroup computers.

    This appliance is Debian 6.0.1a with a stock install and enough
added to get a Coda client running.  It includes the virtualbox
extensions so resizing the virtualbox window resizes the Debian/GNOME
desktop.  All Coda related commands like clog, cunlog, cfs, repair,
and so forth must be done on the appliance.  There is 400 Megs free
on the virtual disk.  100 Megs is the initial Venus cache size.  It
can easily be changed by editing /etc/coda/venus.conf, changing the
"cacheblocks" definition and then restarting the appliance.  This
leaves at most 300 Megs for "user data".

    This appliance should work on Windows Vista and Windows 7 in the
same manner as on XP.  We have not yet tested it in those environments
yet.   Also, this appliance should work in Solaris and Linux environments.
Again, it has not yet been tested in these environments.  If one wanted,
/coda could be exported via NFS instead of Samba/CIFS.   That has not
been set up for this appliance.   Both Solaris and Linux should have 
a method of mounting a CIFS drive into their file system.   It should
be mounted at /coda for consistency sake.


    The following are a list of questions we have not completely answered
and would like some input from the Coda community.

    1) What would be the best approach to building the appliance?  Start
with a small distribution like "TinyCore Linux" and add content to get
a working Coda appliance or start with a large distribution like Debian
and delete unneeded contents to make a smaller machine.  We are currently
considering using Debian as the base and producing a minimal installation
without gnome.

    2) How important is the desktop on the appliance?  Is the assumption
that all it would be used for is just the coda utilities (clog, codacon,
and so forth) or would a fully functional Linux VM be the better way
to go with Gnome and all that it offers?   (A full Gnome installation
would cause a much larger VM image similar to the test appliance listed

    3) Plans are currently to have the appliance just have a guest account
with no password.  The user (again we are assuming a single user machine)
just uses the VM console to clog to their proper Coda user and the
host machine gets access via the guest account.  Thus, no account creation
is needed on the appliance.   This does give every user on the host machine
common access to the Coda appliance.   Does this sound reasonable?  Do you
see a need for appliance accounts?

    4) Although current plans are to have clog, cfs, repair and so forth
available only on the appliance console, would people like to see a native
app/script that brings clog and friends to the host desktop?

    5) How important is having storage space available for the "user" in
the appliance.  The proof of concept appliance has 300Megs of user storage
available.  Is this too much or not enough?

    6) Would people find it useful to have a choice of a small, no gnome
appliance with limited user space (the goal is to have 500Megs or smaller
total appliance) and a large, full gnome installation with 4G (or more)
virtual disk available for user use? (e.g. virtual disk of 8G as compared
to 4G in the current appliance.)

    7) Anything that might make this more useful to you that is not mentioned



Phil Nelson,
Received on 2011-06-16 14:22:24