Coda File System

Re: Coda over ADSL

From: Dushyanth Narayanan <>
Date: Sun, 24 Jun 2001 08:54:20 -0400
> 1. What parameters should I set for rpc2 and sftp for suitable packet 
> queue sizes and timeout values for an ADSL connection like the one I 
> described above?

Hi, I had this e-mail forwarded to me ... since I use Coda over ADSL
from home (though I don't work on Coda). I'm not sure what the rpc2
and sftp parameters should be, but I notice another problem which
I think is deeper.

Coda (or rather rpc2) assumes a symmetric connection when it makes its
estimates of bandwidth (i.e. it does not estimate incoming and
outgoing bandwidth as separate quantities) . Over an asymmetric
connection, this leads to varying and incorrect bandwidth estimation,
which in turn cause Coda to flip-flop between weakly connected (client
writes are logged and sent asynchronously to the servers), strongly
connected (writes are sent synchronously to the server), and sometimes
even disconected (writes are logged locally) state

I tried to fix rpc2 to estimate upstream and downstream bandwidth
separately; however, it didn't seem to improve the estimation
significantly, and I didn't have time to pursue it further. If you are
interested, I can send you my revised bandwidth estimation code.

I would be interested to know if you run up against this problem
(especially if you find a solution!)

Received on 2001-06-24 08:56:29