We’ve been working with some of our partners on using the QNAP NAS devices (detailed in our Rsync NAS Hardware Compatibility List) as an offsite data host.
We’ve had reports that some firewalls can cause problems when port forwarding. Normally, all you’d need to do is to open up Port 22 (SSH) and port forward it to your NAS device. However, we’ve found that on some firewall devices, it causes problems with “Out of disk space” errors.
However, if you use a VPN connection, the error does not occur.
In the meantime, we’ve found a workaround which involves running Rsync in Daemon mode, via a secure SSH tunnel. We’re going to implement this mode in a future release of BackupAssist for people experiencing this issue. The communication is still secure because data is fed through a secure shell tunnel, but the setup is just slightly more complicated.
Note: This problem does not seem to occur for Windows or Linux Rsync Servers, and many of our users are successfully port forwarding to Windows or Linux Rsync Servers. We’ve only experienced it for the QNAP NAS device, which runs embedded Linux.
More details will be provided when our workaround has been implemented and released. In the meantime, we do have a manual method that will make it work, based on scripting.