I'm setting up a VPS that'll host a couple of sites, and I'd like to back up everything to another host which has a nice massive ZFS, allowing me to snapshot frequently.
With the knowledge I have ATM, I only see rsync as a solution since it does delta backups with the -c flag, pretty necessary since this VPS has a limited bandwidth and potentially a quite large dataset, so transmitting everything one or several times a day isn't feasible.
On the other hand, that means that if I need to properly preserve permissions and back up everything, including stuff that's only readable by root (such as SSL certificates), I need to enable authkey SSH root logins on either one of the hosts (and push or pull backups accordingly). And I'd really like to avoid that.
Or do I need to do that? Is there some trick that you know of that would allow me to run some cronjob on the VPS and push out differential backup data to my other host without having to compromise security yet still be able to back up all files and preserve their permissions and ownerships?
I guess a last resort could be to set up a VM on the ZFS host only for this purpose, enable password-less ssh root logins on a non-standard port inside it, make sure its disk image is on ZFS (or is a ZVOL) and then push the backup files to it. But damn, that seems clunky, it would be a hassle to set up, and it'd eat resources on that host.