Two five gallon Jerry cans... sufficient for a BX2230, my only diesel tractor.. and the Kubota is always topped off after use, keeping the tank full to minimize the chance of moisture condensation and subsequent bacteria/crud growth.
A couple of gas stations are a short ways up the road. When I get them refilled, another 5 gallon Jerry can for gasoline for the Ford and a 1 gallon Jerry for chainsaw mix gets filled at the same time. SeaFoam stabilizer gets added.
I used to store more, even had an underground for gasoline years ago that local FCX farm store filled for me, but after getting concerned with the mess I'd have if it ever leaked, I eventually stopped using it and had it dug up.
After having huge problems with the chainsaw getting crapped up from today's limited shelf life gasoline, the cans have tags on them that I write the date filled.. and don't let it sit in storage too long. If I haven't used all the gasoline after about 4 months max shelf time or when the diesel cans needs to be filled, the 5 gallon gas can gets dumped into my 4x4 Toyota and the 2 cycle gas/oil mix gets dumped on the old Ford tractor.. keeps the top end of the engine lubricated.