PLANET NVR-1620 - Manual (Page 61)

Network Video Recorder with HDMI
NVR‐820 / NVR‐1620
61
Disk Status pages in "System Options". The USB HDDs have to be
formatted in advance in FAT16/FAT32 or EXT3 file system. (FAT32
is recommended)
* Please plug in the USB HDD only after the NVR is fully started.
The internal HDDs will NOT be properly detected if the NVR is
powered on with USB HDD plugged in.