QNAP devices behind firewalls – Rsync backup problems

Hi all,

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.

2 thoughts on “QNAP devices behind firewalls – Rsync backup problems”

  1. How does this blog post square with http://kb.backupassist.com/articles.php?aid=3053 which says

    Insufficent space to complete backup
    Last modified on: 30th Jul 2009

    BA706 Insufficent space to complete backup
    This error usually indicates that you’re trying to backup to a store/drive which is smaller than the total size of the backup itself.

    This error has been known to appear when attempting to Rsync to a QNAP� device and creating the backup directory in the 10MB RAM drive instead of the user directory.
    Check the amount of space on the directory which you’re trying to backup to.

    If backing up to a QNAP device.
    Make sure you’re not backing up to the 10Mb RAM drive which is on QNAP brand devices and then change the backup to go to the user directory instead.

    • Hi Will,

      Thanks for pointing this out. I’ve now updated the knowledge base article to represent that firewall and SSH connection issues may also generate space related errors also.

      Thanks again,


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