Coda File System

Re: Trouble clogging from a remote client

From: Jan Harkes <>
Date: Wed, 6 Aug 2003 12:42:29 -0400
On Mon, Aug 04, 2003 at 06:49:46PM +0900, Stephen J. Turnbull wrote:
> >>>>> "Jan" == Jan Harkes <> writes:
>     Jan> Could you send me an strace of the failing clog?
> Not yet.  I rebooted (it's my roadwarrior) and haven't replicated.
> I later saw a listing of /coda which contained only the (numerical) IP
> realm but (d'oh) didn't realize it was the same problem (probably is,
> isn't it?) and rebooted.  Can't replicate that, either.  :-(

Ok that does make sense. Technically you can access the same 'realm'
with many different names. For instance, you can access as


Now because you can't (shouldn't) hardlink directories under UNIX, each
of these 'instances' of the same realm really are different realms as
far as venus is concerned, they just happen to have the same contents.

The only real problem with this is that the server doesn't yet realize
that the client is accessing the same objects from different contexts,
and will only send back a single callback. So in a situation like this
you can easily get inconsistent behaviour when files are modified.

> I think the problem is a bogus configuration on my part, though.  The
> client box in question has both an ethernet interface on eth0 with a
> proper IP and a wireless interface on eth1 which is NAT'ed.  If I boot
> with both interfaces enabled, I have to shut down the wireless
> interface.  The wireless interface doesn't seem to work properly
> alone, either.

That could just be a default route problem. My laptop has a similar
setup. It is either wired or wireless, and the wireless link can be
connected directly (to the campus network), or go through a masquerading
firewall to a ppp-link (when I'm at home).

So as far as servers are concerned, my Coda client is a schizofrenic
with a split-personality. But it still works most of the time :)

Now for Coda servers it is an entirely different story. They rely on
having a single IP-address, as permanent as possible. The server ip
address is stored in the VRDB and VLDB files, and if it ever changes
all servers will need to be restarted and the volume replication and
location databases have to be rebuilt.

> Non-Coda apps like HTTP do work over the wireless interface, but I
> guess that's sort of "by accident", since I'm sure the wireless
> interface doesn't have any existence in the DNS, and my host thinks
> that its name and address are those of the ethernet interface, even if
> the ethernet interface is down.

I've got the same thing. My hostname is always mentor.coda, the DNS
entry matches the wired address, but most of the time it is on the
wireless which is given a dynamic ip by DHCP.

Received on 2003-08-06 12:44:19