Hi there,

On Sun, 22 Mar 2026, George King wrote:

I'm not sure if it's considered a good approach compared with the
other approaches mentioned but I find DeltaCopy Server very easy and
effective to use on my Windows box.? Rsyncd on BackupPC.

Good point.  Some observations:

1. For a number of reasons, as far as BackupPC is concerned, running
rsync on Windows clients is far superior to using what effectively
amount to kludges like SMB.  But it *does* mean that you have to load
software onto the Windows clients, which you don't have to do if you
use smbclient and you can accept some (considerable) tradeoffs, for
example the very dodgy file excludes in smbclient:

https://github.com/backuppc/backuppc/issues/252

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2. As I've never even downloaded Deltacopy I don't feel qualified to
comment on its usability or effectiveness.  Basically I gather that it
is versions (I don't know which versions, and that might be important)
of Cygwin and rsync packaged for easy installation on Windows.  These
tools have commonly been installed by people here on the mailing list
for backing up Windows boxes and they seem to do the job.  ISTR using
them decades ago, most likely Cygwin version 1.something, but I can't
remember where nor why.  I can't remember any big problems with them,
so guess they worked well enough at the time.

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3. I quickly looked through the Deltacopy documentation just now:

http://www.aboutmyip.com/files/DeltaCopyManual.pdf

On page 7 of the PDF manual there's a suggestion that you may need to
open port 873 on your firewall if you're backing up over the Internet.
This recommendation alone makes me question the use of anything from
the Deltacopy stable.  Nobody should ever do that because

(a) it opens up rsync to the world, which is a security nightmare you
really don't want to experience, see for example CVE-2024-12084 and

(b) the data transfers over the Internet would be plain text, which is
of course another security nightmare although possibly not as serious
as some criminal getting remote code execution on your rsync server.

If you need backups to traverse the Internet, some form of encryption
is in my view essential.  My preference is for a VPN such as OpenVPN
(which I use routinely for remote backups and which provides much more
than just a backup path) but you can for example use rsync over ssh by
setting it up in the BackupPC configuration.  The encryption overhead
may be significant.  Using a VPN gives you the flexibility to offload
that work to machines other than the backup server and its clients if
it turns out to be necessary to make the backups proceed more quickly.
It could be the difference between having a backup and not having one.

----------------------------------------------------------------------

4. The documentation gives me little idea which versions of Windows
are supported by Deltacopy.  The page at

http://www.aboutmyip.com/AboutMyXApp/DeltaCopy.jsp

gives under "System Requirements"

* XP, 2000, 2003, 2008, Vista and Windows 7. We have not tested
  DeltaCopy on Win9x.
* 10 MB hard disk
* 64 MB ram
* 1 GHz processor or better

which looks like it could use an update.  It doesn't say for example
that Cygwin dropped support for XP in 2015:

https://sourceware.org/pipermail/cygwin-announce/2015-August/006392.html

that Cygwin dropped 32-bit support altogether in 2022:

https://cygwin.com/pipermail/cygwin/2022-November/252542.html

nor that Cygwin support of Windows 7, Windows 8, Server 2008 R2 and
Server 2012 was dropped in version 3.5 early in 2024:

https://cygwin.com/pipermail/cygwin-announce/2024-February/011524.html

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5. One of the issues people come up against with Cygwin/rsync is that
backing up open files can be problematic because Windows restricts
access to them.  If it's essential to back up open files then people
usually get around this using "shadow copies" of the data, see e.g.

http://www.michaelstowe.com/backuppc/

which links to

http://www.goodjobsucking.com/?p=62

giving a very clear account of one implementation.  This seems to be a
problem that has been fairly well put to bed.

----------------------------------------------------------------------

Other observations invited and very welcome.

HTH

--

73,
Ged.


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