[Gnu-arch-users] Re: The future of GNU Arch users

[James Blackwell]

On Tue, Sep 13, 2005 at 12:48:52AM -0400, John A Meinel wrote:
> James Blackwell wrote:
> ...
> 
> >>I guess what I am trying to say is: Having a dumb file server as a
> >>storage for SCM is a great feature, and it should be extended to the
> >>point of being fully usable.
> >>
> >
> >
> > I deeply agree. :)
> 
> The biggest concern with a remote fileserver is atomicity and locking.
> It can be tough to get that right if the protocol doesn't natively
> support it. (SFTP v6 does, I'm not sure about v3). I don't think ftp
> gives you much of anything, http is pretty much download only without
> webdav.

Yeah. As you're no doubt aware, the same problem existed in baz, but was 
mitigaged somewhat by creative usage of directory creation. 


> Right now, the storage mechanism is to put each revision of every file
> into a separate gzipped file. Which means you have a fairly safe
> structure, which can be handled fairly easily from remote.
> In the future, some of the possible storage formats (weave/revfile)
> could change that. They would either be append-only, which means that
> the remote protocol needs to support appending to an existing file, or
> possibly completely changing (which can mean just uploading a new file,
> and then renaming it in place).
> Anyway, with the both weaves and revfiles, you have to worry more about
> not having 2 processes mess up a remote system by writing at the same time.

I've been very curious about how concurrancy was going to be handled,
especially i the case of weave. 

There's a number of people out there for which even something like pqm is
too complex. They're expecting that some day multiple people are going to
be able to push to the same place. 

The supermirror also has plans for multiple committers to an archive. If
baz-ng isn't able to do it then its going to have to resort to nasty
alternatives like having logic like preventing simultaneous 
scp logins to archives.


-- 
 James Blackwell      |   Try out the blog planet for revision control
 Tell someone a joke! |   at http://planet.revisioncontrol.net
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