You could use something like Rackspace cloud sites: http://www.rackspacecloud.com/cloud_hosting_products/sites
They claim to offer automatic scalability and server redundancy out of the box. I have no personal experience with this product thou.
They claim to offer automatic scalability and server redundancy out of the box. I have no personal experience with this product thou.
I have this service but don't use it for anything serious. The primary win is that I don't have to maintain the servers, and the email service is very solid with a good webmail. Downsides are I can't make them switch to PHP 5.3, the filesystem is NFS, and there's no API for the control panel stuff. (Most hosts don't have an API for control panel actions, but it would be nice if I could automate creating sites.)
My first startup was a hosting company -- my partner still runs it and I exited a few years ago. Having "been there and done that," I have a lot of respect for anyone that can stay in the hosting business -- when everything is running just fine, your customers are complaining about why things can't be cheaper. As soon as the network blips for even a second, everyone's talking about how crappy the network is, why they pay so much (even on $10/mo accounts), etc.
In other news: it's early, I can't sleep and I might be a little cranky. :)
That said: my point wasn't so much that Rackspace is a bad hosting company, but rather that the original question was looking for a solution that would offer really close to zero downtime for their customers, and given that, "put it all on Rackspace" isn't a viable answer.