SSDs have become fast, except in the cloud

This was a huge technical problem I worked on at Google, and is sort of fundamental to a cloud. I believe this is actually a big deal that drives peoples' technology directions.

SSDs in the cloud are attached over a network, and fundamentally have to be. The problem is that this network is so large and slow that it can't give you anywhere near the performance of a local SSD. This wasn't a problem for hard drives, which was the backing technology when a lot of these network attached storage systems were invented, because they are fundamentally slow compared to networks, but it is a problem for SSD.

Why do they fundamentally need to be network attached storage instead of local to the VM?

Because even if you can squeeze 100TB or more of SSD/NVMe in a server, and there are 10 tenants using the machine, you're limited to 10TB as a hard ceiling.

What happens when one tenant needs 200TB attached to a server?

Cloud providers are starting to offer local SSD/NVMe, but you're renting the entire machine, and you're still limited to exactly what's installed in that server.