Consider a banking systems that has 4000 ATMs situated across many places in a particular region. The bank customer can carry out many transactions like balance check, money withdrawal and deposit,...

Consider a banking systems that has 4000 ATMs situated across many places in a particular region. The bank customer can carry out many transactions like balance check, money withdrawal and deposit, password reset. These transactions takes 4, 8 and 6 bytes respectively. Each of this transaction has a timestamp attached to it which takes 8 bytes. This transaction data needs to be stored at different places like at ATMs, at an immediate buffer at streaming system side and in a persistent storage. Narrate the three use-cases which require the data to be stored at these three places and estimate the sizing required for the same and suitable option for the storage