Resource needs for zeroes vs. alphas in kubernetes

I am planning to use kubernetes to build an HA cluster, and I am starting from the config here:

I see that I need a persistent volume claim for all three zeroes and all three alphas, and I see that all are set to 5Gi. If I wanted to support a lot more data, does only the alpha volume template need to increase in size, or do the zeroes and alphas require the same amount of storage space as the data scales up?

What about CPU and RAM? Do the needs of zeroes and alphas scale together, or are those resources more valuable on one or the other?