Coda File System

Re: CODA and crash recovery

From: Yves Dorfsman <>
Date: Tue, 01 Jul 2008 22:34:19 -0600 wrote:

> First a word of caution.
> In my experience it is not crash recovery which is the crucial point
> for migration from NFS to Coda. The hard part is the education of the users
> and their readiness to cope with conflicts. This can be painful unless
> there is expert help available to the users - conflicts can be still tricky
> to resolve for a user on her own.

Thanks, I had not thought about that, on the other hand, I don't expect the 
directories I'm going to share to create a lot of conflict.

> Server planning and administration is also very different from NFS
> so it may take time to design a viable Coda realm setup.

Yes, I understand that, and am playing around with different ideas right 
now, which also help me to bridge the theory with the practice (I've 
completely recreated my config about 5 times already).

>> So, how does CODA typically handle a machine crash ? Is it completely lost 
>> and need to be recovered from dump/backup ? Does it need to be fsck'ed ? 
> Do you mean a server or a client?

Sorry, I meant server. I was assuming only one server (coming from NFS), and 
will eventually move important files to it, and don't want to spend too much 
time getting the server going in case of a hard crash. Reading your email 
and thinking more about it, I realised that I could use one of the 
workstation as a secondary CODA server - neat.

> Essentially, neither of those need any special treatment after
> a hard reboot, given that the local disk file system is not corrupted
> (journalled or/and successfully fsck-ed)

So, at least to satisfy my curiosity, assuming the server act also as a 
client, that while a process is writing to that filesystem you were to pull 
the power cord. The process was in the middle of writing, and the underlying 
FS is a logging FS, so the underlying FS is in a consistent state, is that 
enough to guarantee that the CODA FS will be in a consistent state ?

>> How often do you typically do the dump ?
> I don't (if we think of the same "dump"?)

I was thinking server side CODA volutil dump.

>> What's the advantage of the dump ?

>> My guess is that if you recover from a backup (vs. a dump), then you have 
>> to recreate your volume on all your servers and clients as if it were a new 
>> one, right ?

Received on 2008-07-02 00:36:45