Coda File System

Behaviour of coda with large files

From: Martin Ginkel <>
Date: Mon, 27 Feb 2006 13:39:30 +0100

I am using a simple coda-setup and I am trying to store some larger
files (ISO-Images) >500M < 2G  on a volume.
The client and server are are different machines and the server is
IMHO strange things happen:

If I copy a file on the client into coda, the client first writes to
the local cache and then starts transmitting the file contents, when
the local op has finished.
OK, normal. The transmission is quite slow:
It does by far not use the available bandwidth
(100Mbit net, coda write traffic uses up to ~7 Mbit).

1) First odacon reports something about a store operation.
If this finishes successfully, everything is fine.
If something (like a disconnect) disturbs this "store", the file will 
apparently never reach the server (see below). During this longer store
operation (about 15min) the server responds normally to Probe calls and 
seems to be alive to the clients.

2) After some disconnect within the store the client will
eventually reconnect to the server and start a reintegration
(reported in codacon). Then a 'backfetch' is reported.
The speed is the same as above.
When this operation starts, the server becomes *unreachable* to 'Probe' 
attempts from any client!
If this happens the client will disconnect from the server, although it 
still transmits (slowly) the file contents. The server will after a
while also drop the connection to the client.
The transmitted data is then never reintegrated into the volume on the 
server, but after sending the whole file, the server will be reachable 
again, and restart the reintegration, when the respective volume is hit
on the client. Again and again ...

a) I guess this is not wanted?
    Why is backfetch blocking the other calls and store is different?
b) Is there a way to improve the performance. What is the bottleneck?
    Are there tuning parameters? Or is it just due to RVM?

All things happened to Coda 6.0.14 running on kernel 2.6.9 with
100 Mbit Network and 0.8-3.0 GHz Processors.
server RVM has 40MByte Size and can fit fully into RAM
(although only 10M RSS are used now).

	Any hints are very welcome


+-[Martin Ginkel]-------------[mailto:mginkel(at)]-+
| MPI Magdeburg, Zi S2.09    Sandtorstr. 1, D-39106 Magdeburg, Germany |
| There ain't no devil, ther'e just God when he's drunk. Tom W.        |
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Received on 2006-02-27 07:45:35