Coda File System

Re: reliability,performance ?

From: <>
Date: Wed, 30 Aug 2006 11:00:40 +0200
Hello Michel,

Coda is my file system of choice but I want you to be cautious.

On Wed, Aug 30, 2006 at 10:06:11AM +0200, wrote:
>  * 2 GB file-limit on linux. I've read that there is a patch for windows,
> but the question is how long before a stable patch wil be merged with the
> linux-code?

"Big file support" has essentially not much to do with 2G limit.
Currently it is no more than a test of one of many possible solutions to make
bigger (not necessarily over 2G) files available via Coda, readonly,
only in connected mode - without fetching the whole file into cache.

With other words, it is a try to implement some limited "non-Coda" semantics
using Coda with minimal changes.

That has probably little in common with your needs.

>  * The faulty re-integration you mentionned that happens from time to time
> it seems. This is a bad one or can it be detected and solved manually (at
> least it is detected and solvable then).

Conflicts can be solved manually.
In some cases you have to use another client to be able to resolve
a complicated conflict.
In some cases you have to do more complicated actions like saving a local
copy of the file from Venus checkpoint data, purging the object and
rewriting it.

Taking the above into account, the risk of actually _loosing_ data is low.

> We need the distributed filesystenm to eventually (can be within a month
> or later) store terabytes of data. I don't think that this is a problem
> with coda.

It is no problem given:

1. files are big themselves, but under 2G each
2. there will be no concurrent updates on files (otherwise you get conflicts)

Count with being able to store about 10^6 files on a single server,
so you can calculate how many servers you will need for all your files.
Multiple servers can be run on a single machine, but you will need lots
of RAM for their RVMs and separate ip-numbers for each server.

> ASR seems to be nice. Reintegration of subversion-repositories could maybe
> be done by using subversion-merge or so in my case.

I doubt somehow that subversion plays nice with Coda. Use git instead
and you will be fine.
Note that ASR is in its early stages and nobody runs it in production yet.

As a general note, software relying on locking for consistent access is hardly
compatible with Coda. Check if yours is.

Regards, Rune
Received on 2006-08-30 05:02:34