Renamed files and directories

[Jamie Lokier]

David Howe wrote:
> N.J. van der Horn (Nico) wrote:
> > What is the current status of both rename-patches ?
> > Are there alternative measures ?
> > 
> > Frequently users reorganise directories and files.
> > Recently a directory of 40GB was renamed...
> > It took 3 weeks to re-copy all over an ADSL-link.
> > 
> > I have followed the last couple of years the postings,
> > and realise it is not as easy as it seems.
> > But the users do not understand this at all 8-(
> 
> Hi all,
>   Only recently joined the list - so haven't seen the last couple of
> years worth of postings. Would there be a summary of the issues anywhere
> handy? I have a customer who has issues similar to Nico regarding
> directories being renamed with large amounts of storage needing deleting
> and re-creating in a "stock" rsync install...

There are methods to perform efficient updates of large numbers of
files and a large amount of data, across simultaneous renames, copies
and edits.  But that is the realm of "similarity detection indexing",
which is beyond the scope of rsync.  At least with the present design,
which doesn't use persistent indexing of any kind.  (This is a feature!)

But when it's good enough to match files which have been renamed
without edits and without changing modification time, it seems
reasonable enough for rsync to have an option to detect those.  It's
expensive, because it would have to scan the whole directory tree at
both ends before transferring anything, and it would have to keep a
little information about every file in RAM at once.  But imho it's a
reasonable option to ask for, if someone wishes to write it.

For myself, if I do a big rename of some directory tree, I try to
remember to rename it manually at the destination too, before
running rsync.

-- Jamie