Edge recording is one of the best features ever developed by the video security industry.
Having it in place insures backup, fail over, and resiliency if planned and wired correctly. Someone comes in and steals the NVR / BI PC.
Not the end of the world as the onboard memory is in place to offer you that insight. How about if the NVR / BI PC had a drive / network failure?
No problem hardware that supports ANR will backfill the missing time line or worst case allow you to export the same!
Trouble Shooting: Things are missing or strange behaviour is present? Whelps, not a problem because you can compare what’s captured on the individual camera to see if that problem is seen or not.
Could be a switch that’s dropping packets but has enough power to sustain the camera but none of the data is streaming into the local NVR / BI PC!
Regardless of all the pros of doing this. Don’t cheap out and buy improper storage media. The best are called industrial, the next best (marketing name) is High Endurance.
Anything that is advertised for dash cameras / video surveillance is a sure bet. You’ll need to balance capacity, value, and warranty.
Anything that indicates a lifetime warranty like the industrial Micro SD cards is using the latest memory that incorporates wear levelling, power management, ECC, write / read protection, and health stats.