Re: [9fans] CMS/MMS (VCS/SCM/DSCM) [was: syscall 53]

[erik quanstrom <quanstro@quanstro.net>]

> > another key point is that all distributed scms that i've used clone
> > entire systems.  but what would be more interesting is to clone, say,
> > /sys/src or some proto-based subset of the system, while using the
> > main file system for everything else.  imagine you want to work on
> > the kernel, and imagine that you keep console log files.  clearly
> > you want to see both the new log entries, and the modified kernel.
> 
> Actually with something like venti as the store, `clone' is
> trivial! Just find the hash for a particular changeset you want
> to clone and you can build the rest on demand. `rebase' or
> `pull' will be more painful.

venti is going to be a difficult model.  the objects in scm are typically
arbitrarly sized, and have arbitrary metadata.  θfs has this model for
its object store.  venti does not.

> > i would be concerned that this really challenges the plan 9 model
> > of namespaces.  one would have to figure out how to keep oneself
> > out of namespace hell if one were to build this into a file system and
> > use it heavily.
> 
> Your concern is a bit premature.  We are just handwaving right
> now!  I am interested in finding out just how far we can push
> the plan9 model -- and if the current model doesn't naturally
> fall out of any extended model, we'd know.

i don't know.  this concern was addressed in the very first paper,
and i have delt with some plan 9-based systems that did this, and
didn't get it right.  

but it can be addressed without much trouble.  just have the fs export
em all.

- erik