Backup scripts - recycling old backup directories (Kevin Korb)

[Perry Hutchison]

Robert Bell <Robert.Bell at csiro.au> wrote:

> > 2. Metadata history.  If there is an existing file in the target dir
> > that differs only by metadata (permissions, ownership, timestamp) then
> > rsync will simply change that metadata.  That change affects all
> > instances of that file.  Of course this is better for storage space as
> > the alternative is storing another copy of the file with the different
> > metadata but we decided it was better to have that information saved.
> Yes.
>
> I would love to see someone make a patched version of rsync to allow
> callers to select a different behaviour in this case!
>
> So, if a file has identical content on source and destination but
> different metadata, then if --link-dest is in use and the link count on
> the destination is > 1, then take a new copy from source rather than
> just updating the metadata ...

Or you could arrange to store the content and the metadata
separately, so that all files having common content -- or
similar large content with small deltas -- can share a single
instance of that content.

There is a rather well-known subsystem (toolkit, really)
which already provides this capability:  git.  Figuring out
the details of using it as a back-end for rsync backups is
left as an exercise :)