Author here! Well that's embarrassing, you're right about the 7 million number. I've updated the post to correct it.
We'll be following up in a later blog post on the numbers we use for Route 53.
Off-topic: ^W is more efficient and carries the same connotation of a strikethrough. I only recently found out about ^W myself, so am curious whether you actively chose ^H (character delete) over ^W (word delete), or whether this is something that people don't know about as bash/emacs commands?
I feel that ^H is more widely known because those are the actual characters that people used to see in older terminals before remembering to type "stty erase ^H".
I used ^H because that has become the standard way to indicate a "correction" for humorous purposes. As to why that became the standard, it does go back to the days before Delete keys started going where the Backspace key is supposed to be, requiring that the erase character be set to DEL to compensate. It has nothing to do with emacs.
Isn't the number used later in the article incorrect too?
The article says: "Thus the real impact is constrained to 1/56th of the overall shuffle shards."
Shouldn't it be 1/28th?
It's 8*7 / 2 since the permutations "shards x, y" and "shards y, x" are the same as far as fault-tolerance is concerned.