Can't keep site live

The most common reason for high IO usage is backup plugins. Those plugins work by collecting and storing a copy of your entire website, which puts a lot of stress on the storage, hence the high IO usage.

And what do you know: you have Updraft enabled on your site.

Please disable that plugin and any other plugins which make backups or otherwise read and write a lot of data, and check if that helps with IO usage.

EDIT: There may also be a system issue related to this, I wrote about that here:

It doesn’t change the fact that Updraft and other backup plugins generate high IO usage.