Re: [Duplicity-talk] Pretty pictures and new version of proposal

[Will Dyson]

On Mon, 2003-09-29 at 03:17, Ben Escoto wrote:
> Hi all, thanks again for your input.  I have updated the page at:
> 
> http://www.nongnu.org/duplicity/new_format.html
> 
> and put in some more detail.  This version tries to be both more tape
> friendly and more file system friendly.  As always, if anyone has any
> comments (for instance, you think keeping two copies of file metadata
> is excessive---see the page), I would be happy to hear them.

Nice pictures :)

I wonder if the need for two copies of the metadata could be avoided by
having the index file only contain pointers to the actual metadata
stored at the beginning of each file.

This would make it harder to list the contents of the archive, since
lots of pointer chasing would be needed. Particularly a problem with
streaming media. But perhaps most folks with archives on tape would be
fine with listing the archives in the old-fashioned (tar) way? Can most
tape drives even seek to the start of the index file at all?

I like how putting the directory contents only in the index's version of
the meatadata solves the problem of having to know the offsets of files
yet to be written. That is an argument for the redundant metadata.

For the sparse file support, I wonder if it might better to leave it out
and assume that anybody with large sparse files (and the common sense of
tofu) would think to encode the inner file with a compression method.

-- 
Will Dyson
"Back off man, I'm a scientist!" -Dr. Peter Venkman