http://www.ananova.com/the-importance-of-a-backup-plan/

It’s the moment you try with all you have to avoid, but there’s absolutely nothing you can do: your shared hosting website has gone dark due to a hosting provider outage. Although you can research companies for months in order to find the one with the least amount of outages, you’ll never find one with 100% uptime guarantees. It’s just not possible (and if you find one, stay away! They are lying to you!).