The root file system on Synology NAS devices is NOT designed to be used by end users or third-party developers. When installing Netdata, the installation script places Netdata files and directories inside the /opt directory area. This is unfortunately, NOT SUPPORTED by Synology. I discovered this during a support call to Synology Support. They also do NOT support end user manipulation of the root file system size. The reason for this is that the root file filesystem is small and is managed during Synology DSM upgrades. Current Netdata installations have been squeaking by with the root file system growing to 90%. Not exactly a good place to be.
There are some other comments related to this in other posts, both in this forum and in other internet discussions. For the moment, I’ve linked the Netdata installation files into a directory under the end user file system (typically /mnt/volume1) from /opt as a work-around. I strongly suggest that Netdata engineering coordinate with Synology engineering to get this app properly installed in the existing package infrastructure. It would be even better to join their deployment topology so that Netdata becomes a semi-supported application.