very simple datastore reimplementation

Jim Gettys jg at
Thu May 8 10:22:54 EDT 2008

On Thu, 2008-05-08 at 16:06 +0200, Tomeu Vizoso wrote:
> On 5/8/08, Jim Gettys <jg at> wrote:
> > On Thu, 2008-05-08 at 13:09 +0000, Tomeu Vizoso wrote:
> >
> > > I'm having trouble understanding what you are requesting and what
> > > could be done about that.
> > >
> > > Can you please enumerate the requirements that affect the internal
> > > file layout and any other view that we may be able to provide?
> >
> > That there is *some* hope of finding a file by a human in a raw file
> > system, that can be done with software already present on the system....
> With the proposed metadata text file, there's already that hope. You
> think it's not enough and you may very well be right. What I'm asking
> is: how big an effort are we willing to devote to this and until which
> point we want to compromise on robustness and simplicity?

Until we know what the tradeoffs really are, we need to explore in this
direction.  Names only as hashes has proved to be a major headache in
practice in the field.

> > This may be to enable manual retrieval in backups (without having to
> > restore everything) as well as interoperability.  Just having a name
> > that is a hash makes this tough...
> Is it ok if only the last version of this file is available in that
> way? Past versions may be stored as reverse deltas

I don't see what the fact the file might contain a delta would have to
do with with the naming, though, certainly being able to easily
distinguish the most recent file from older deltas by the name is
something humans would like to be able to do.
                         - Jim

Jim Gettys <jg at>
One Laptop Per Child

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