Anran POE Security Camera System - When HDD is full, do I need to delete recordings?; Which hard drive does POE security systems use?; HDD not found or not recognized error.

3: Open the NVR box, double check if your system has a pre-installed hard drive.
If your NVR is Cylindrical, you can check by the following link of video:
https://drive.google.com/open?id=1o9h47TlEvBjXmMCGGV3HhtuNgMv4KywS
If you still cannot find the hard drive, you can contact our tech support to have a
further checking via support@anran-cctv.com
Q2: When HDD is full, do I need to delete recordings?
A:No need, It's loop recording, that means it will auto overwrite when the hard drive
is full.
Q3: Which hard drive does POE security systems use?
A: ANRAN POE Security Camera System supports up to 4TB HDD (Internal, SATA
Interface, 3.5 inches)
Q4: The system includes hard drive. Why it shows "HDD not found" or
"HDD not recognized"?