1 to 7PB
When working for BT in 1981 I asked a customer what the purring noise was. He said it was his Winchester HD. I asked how much memory it had.
He puffed out his chest & said it had 10MB.
I said, "What do you need so much memory for?"
I had just bought 32kb memory for my ZX81 & the guy in the shop had asked me the same question!