I'm in the process of experimenting with BackupPC on a CentOS 5.5 server. I have everything pretty much setup with default values.

I tried setting up a basic backup for a host's /www directory. The backup fails with the following errors:

full backup started for directory /www
Running: /usr/bin/ssh -q -x -l root target /usr/bin/rsync --server --sender --numeric-ids --perms --owner --group -D --links --hard-links --times --block-size=2048 --recursive --ignore-times . /www/
Xfer PIDs are now 30395
Read EOF: Connection reset by peer
Tried again: got 0 bytes
Done: 0 files, 0 bytes
Got fatal error during xfer (Unable to read 4 bytes)
Backup aborted (Unable to read 4 bytes)
Not saving this as a partial backup since it has fewer files than the prior one (got 0 and 0 files versus 0)

First of all, yes I have my ssh keys setup to allow me to ssh to the target server without requiring a password.

In the process of troubleshooting, I tried the above ssh command directly from the command line, and it hangs. Looking at the end of the debug messages for SSH I get:

debug1: Sending subsystem: /usr/bin/rsync --server --sender --numeric-ids --perms --owner --group -D --links --hard-links --times --block-size=2048 --recursive --ignore-times . /www/
Request for subsystem '/usr/bin/rsync --server --sender --numeric-ids --perms --owner --group -D --links --hard-links --times --block-size=2048 --recursive --ignore-times . /www/' failed on channel 0

Next I started looking at the rsync flags. I did not recognize --server and --sender. Looking at the rsync man pages, sure enough, I don't see anything about --server or --sender in there. What are those in there for?

Looking at the BackupPC config I have this:

RsyncClientPath = /usr/bin/rsync
RsyncClientCmd = $sshPath -q -x -l root $host $rsyncPath $argList+

And for the arguments, I have the following listed:

--numeric-ids
--perms
--owner
--group
-D
--links
--hard-links
--times
--block-size=2048
--recursive

Notice there is no --server, --sender or --ignore-times. Why are these things getting added in? Is this part of the problem?