I have a small synology NAS. I did set up a cron job and that is running fine. I am just having trouble identifying what needs to be backed up. I took the old HDD I was using and formatted it. When I put it in the HikVision DVR it said it was unformatted (this I expected) but when I allowed it to format it the old file structure with the old recordings came back immediately. So beyond the fact that the file dates have nothing to do with the recording date, and that I couldn't find any way to discover the recording date, I couldn't even force the system to drop the old files, even through (quick) formatting. The device must be writing the sectors directly, circumventing the OS/FS