So, I am planning to set up a Raspberry Pi based storagenode ( Raspberry Pi 4 B rev 1.2, 8GB)
What amount of disk space I need for my 100/100 Mbps bandwidth and what configuration, types of disks best for this storagenode?
The best would be whatever drives you already have.
When you run on a pi, you should choose an external USB 3.0 drive with dedicated energy supply . If your external drive is powered by usb only, the Pi might not be able to handle it.
With your setup you can easily fill 14 or more TB. So for example you could buy 2 x 8TB external drives or even bigger ones.
I am running a raspberry pi node on a new location now with 2 x 12TB WD Elements.
As said, use what you already have.
If you absolutely want to buy something, check out current sales for external 3.5 inch drives while avoiding disks with the SMR recording mechanism.
Some external HDD series are known to contain certain enterprise 24/7 rated drives which potentially have a longer lifespan. Google it, the keyphrase here is “shucking HDD enclosures”, for mor especific info.
Look at WD Elements…