I just upgraded from PRTG 14 to 22.214.171.1242, and have run into a new problem with pre-existing SNMP Disk Free sensors. On Linux servers with a btrfs filesystem, the sensors report a disk space error, because the inode channel shows zero inodes. When I checked the servers, I discovered that "df -i" also reports zero inodes. This is wrong, and these servers all have plenty of inodes available. So this looks like a bug in the implementation of btrfs on Linux, or in the df command.
This is obviously a problem with btrfs, not PRTG, but I still need to be able to monitor disk space. The only solution I can come up with would be simply to delete the inode channels in the sensors, but it appears that I can't do that. Is this something that could be implemented? Or is there an alternative solution that I'm missing?