First hit in the forum search: Node Redundancy
However it would be better to investigate why your pi lock up.
The PI I'm using is running fine, maybe one's a year something strange that requires a reboot.
Most problems are related to bad power supply.
Check your power supply, and after that check you power supply again. Buy a good power supply with enough amps.
Also buy a good Pro endurance SD card https://www.amazon.com/Samsung-MB-MJ32G-MicroSDHC-UHS-I-Memory/dp/B07CY3QSST , not to small in size.
