I call it the potato starvation since Ireland was a net exporter of food, grain and meat, the whole time. They just weren't allowed to eat any of the (mostly absentee) landlord's produce. They could only eat what they could grow on their ever less fertile soil. I did not even know this fact until I was about 50, though my father was a student of Irish history. He gave me a book to read, Paddy's Lament, written seemingly without bias, that I recommend to anyone who would like to learn more about this era.
Heh, the whole title of that book is "Paddy's Lament, Ireland 1846-1847: Prelude to Hatred". I'm sure there's no bias in that...
I agree, Ireland was an exporter of food, but it had been for many years. That didn't change. The landlords were in debt too, and would have lost their land (pledged as collateral) if they had not paid their debts.
There was little else that could have been done. Rotten situations are like that: barely tolerable for a long time, and then go all to heck all of a sudden when something unexpected makes a barely tolerable situation horrible. The nature of tragedy is that good people do the best they can, and still horrible things occur.