Can you go into more details? This has always worried me about hosting in general - for sites that can't justify multiple servers, or the complexity of setting

Can you go into more details? This has always worried me about hosting in general - for sites that can't justify multiple servers, or the complexity of setting up MySQL replication, what's the best approach for HA? There's a lot of businesses that fall into this 'important and profitable but not that profitable' range...