cygwin rsync windows to windows ACL problem

[Matt McCutchen]

On 10/1/07, Stephen Zemlicka <stevezemlicka at gmail.com> wrote:
> Let's get terminology out of the way first.  The computer
> sending data is the client and the computer storing the backups is the
> server.

No, you may be pushing, but Havoc is pulling.  Look at the command in
the original message:

> I am running: rsync -avPA //src_addr/some/path /local/dst/path/

The source path is remote, so the sender is the server and the
receiver is the client.

> Rsync needs to read the whole file stored on the server to know
> what data the client needs to send.  Since you are only running rsync on the
> client, the entire file needs to be transmitted from the server to the
> client, then read and analyzed.  Then, a partial transfer may occur.

Please call it a "delta transfer".  A "partial transfer" is a transfer
that is interrupted because rsync is killed or the connection drops,
etc.  Partial transfers are unrelated to the delta-transfer algorithm
and are governed by --partial and --partial-dir.

> So you
> can do a partial transfer but before that is possible, the client needs a
> full transfer from the server to see what it needs to send.

Your explanation is correct only for a push.  For a pull, the trouble
is that there is nobody on the remote sender to tell the client that
data from the source file matches one of the client's block checksums,
so the client can't do better than pulling the entire source file.

There is a "reverse" delta-transfer algorithm that can pull
efficiently from dumb servers.  Zsync ( http://zsync.moria.org.uk/ )
implements this algorithm, but I don't think it is nearly as capable
as rsync in other areas.

Matt