No, I understand that replication is the double cost.

I meant cloud solution should not have storage failures which causes data loss.

A lot of people do (incorrectly) assume this sort of thing, even in cases when it would only take cursory understanding/research to spot the limitations a given service has and where it might fail in a disaster recovery situation.

No matter how good you think a given "cloud" solution is, no matter how much too big to fail you thing the company responsible is, you should make use of the redundancy options they provide and make sure you have reasonable backups elsewhere too (local to you or on another completely separate remote service).

This is what made me dismiss Google's App Engine when it first turned up (I've not looked for some time, they may have addressed this concern long ago): there was no easy way to backup all your data to another location/service and the not-so-easy ways would probably all end up costing a fair bit in bandwidth charges.

This kinda highlights the problem with "cloud"...many people, even engineers, don't really understand what they're getting into. At least with a single server, you know what you're getting, and you have only yourself to blame if you didn't plan for a typical, known, documented failure mode.

… and magically do it at no extra charge, too. Some learning experiences are in order.