Coda File System

Re: difference between replicated and nonreplicated shares

From: Ivan Popov <>
Date: Mon, 12 Jul 2004 16:56:27 +0200
Hello Andrea,

On Mon, Jul 12, 2004 at 01:41:33PM +0200, Andrea Prunic wrote:
> To explain: we have a bunch of computers in our company where we keep 
> music files, for example, and we want to share all of those directories 
> so that anyone can access anybody's directory, no matter where it is 
> physically located (on which computer) but without logging to every machine.
I read it as you want to share many files located on lots of workstations.

> Now, coda is supposed to do that, but I don't see how.

Not really.
Coda is supposed to present a file space to a lot of clients,
while physically the corresponding disk memory is connected to
relatively few, trusted servers.

You have to trust your server hosts enough to let them to
share a common secret (which should remain secret to the rest of the world)

> When I create replicated volume, everything I put under 
> /coda/ goes to every other server (machine) 
> that is a part of the cell.

No, it goes to machines holding replicas of the corresponding volume.
There could be as few as 1 replica (a common test scenario) or up to 8
while more than 3 is usually impractical.

> On the other hand, if I create a non replicated volume, say on root 
> server, I can't use it, because when I try to put something in it, venus 
> crashes (why?)

I think "non-replicated volumes" are nothing but a remnant from AFS.
There is no reason to use them, fast in the past there were such
recommendations. Forget it. Use singly replicated volumes.

Cannot guess why your venus crashes, unless you would supply more details.

> I have server and client installed on every machine, so that anybody can 
> share a part of it's file system and put it as a volume in the coda tree.

A Coda realm is "centrally" administered, you should not let everybody
modify it (unless "anybody" above implies only system administrators :)
A power over the realm is not the same as a power over a workstation,
it is the power over all servers (workstations in your case).

A Coda realm can have any number of servers, with volume replicas
arbitrarily placed on them, each volume as one or more replicas on 
some host(s). Still, all of these machines have to be administered "as a whole".

> codaroot
> |
> |---/|
>                                         |---volume1 (on machine1)
>                                         |---volume2 (on machine2)
>                                         |         |
>                                         |         |---volume3 (on machine2)
>                                         |
>                                         |---volume4 (on machine4)

No problem to do that itself, but Coda is probably not a good solution
for gathering workstations' disk space together.

Best regards,
Received on 2004-07-12 10:59:00