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I've just recently installed Coda, and must say that i'm less impressed with
it compared to NFS for a number of reasons. There is a server setup I will
be doing in a few weeks where Coda will be the only choice, so dont think
that I'm being completely against Coda, I just feel the range of areas where
it is usable is fairly narrow.
1> NFS is already in the linux kernel as is Coda, but Coda is an older
version (5.3.xx vs current 6.0.xx, make sure your user-space code is right
for your kernel module)
2> NFS -- setting up the client and server is a no-brainer, webmin handles
both if you dont want to get your keyboard dirty, and even if you hand-edit,
its no problem, no such luck with Coda
3> Coda's main strength is replicated servers, But you can do the same with
NFS if you are willing to accept some delay before changes propogate to the
other NFS servers (i.e. rsyncing the nfs servers every so often, using
heartbeat failover to bring the backup NFS server online as needed) -- if
your files on disc are frequently changing and replicated servers must be in
sync, Coda is the better choice.
4> Coda's main weakness IMHO is the hoops you have to jump through when you
make changes to the server system -- you have to kill and restart the client
daemon on each client machine to get changes to take. (adding a new server
or replicate, creating or deleting volumes, etc -- experiment a lot on
non-production systems, get the production setup right the 1st time)
5> Coda does much more in the way of local caching than NFS, and the cache
size is configurable... make the cache as large as the distributed filespace
and it is possible to continue to operate if all the servers are down, and
any changes will be committed when one or more of the servers come back
online (presuming all the files needed are in the cache)
6> Coda does not use system uid/gid for its file -- it maintains its own
user/pass database, and you must login/acquire a ticket before accessing
Coda volumes -- NFS runs off the existing uid/gid system, all you have to do
is keep the passwd/group files on all the machines in sync for key users, or
setup NIS+
In closing, I feel that I had a bad experience with Coda, but I wont
hessitate to try again when I have more time to dig into the detail, I was
under a lot of time pressure on this latest job, so I went with NFS just to
get the system online NOW :)
----- Original Message -----
From: "Ariyo Nugroho" <ariyo@xxxxxxxxxx>
To: "Karl Kopper" <karl@xxxxxxxxxxxxxxx>; <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Saturday, November 01, 2003 12:47 AM
Subject: Re: Choosing distributed filesystem
> On Sat, 2003-11-01 at 04:50, Karl Kopper wrote:
> > Yes, I think that is correct. We are probably having this difficulty
because
> > of a lack of a consistent definition of the term "distributed file
system."
> >
> > Here is the configuration I'm referring to:
> >
> > ______________
> > [LVS RS 1]-------------> | NAS |
> > | Server |
> > [LVS RS 2]------------> | |
> > | (NFS Server) |
> > [LVS RS 3]------------> |_____________|
> >
>
> Aha. Thanks for your diagram Karl. Now I know what the HOWTO means by
> saying that each realserver is a client to the distributed filesystem.
>
> BTW, before NFS, have you ever tried Coda or Intermezzo? In the NFS
> HOWTO, it's mentioned that NFS 3 is still lacking some feature that Coda
> has. (And also, Intermezzo claims that it's inspired by Coda. So, it's
> better than Coda). NFS team say that they will cover the lacks in the
> next NFS version 4.
>
> So, do you really mean that anyhow NFS is still the best choice? Oops..
> I forgot to ask: which version of NFS do you use?
>
>
>
>
> Ariyo
>
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