But it wasn't the overloaded shard that brought the site down (it was only slowing things down), it was the addition of the new shard: "For reasons that are no

But it wasn't the overloaded shard that brought the site down (it was only slowing things down), it was the addition of the new shard: "For reasons that are not entirely clear to us right now, though, the addition of this shard caused the entire site to go down."