Re: Even those that can...
Private Cloud == Potentially-Good
Public Cloud == (for most purposes) Bad
* If it breaks, you and your staff can not (are not allowed to) fix it, but you will probably be held responsible.
* Your data-in-the-cloud are vulnerable to sniffing, copying, and denial-of-service.
- Incompetent/inexperienced/underpaid-and-indifferent cloud-provider IT staff (minimum-wage monkeys who don't get active when they see Joe Backhoe tearing up the street outside their atacenter)
- Corrupt cloud-provider IT staff ("Hey, Mr. Cloud-Provider IT Guy/Gal! We'll give you $10,000.00 if you give us a copy of Company X's data.")
- Corrupt gov't in the place where your data are physically stored
- Armed business or gov't conflict in the place where your data are physically stored
- What are the data-protection laws (or lack thereof) in the island-nation of Vuanatu, where your data may be stored?
- Untested-by-you-and-your-staff backup/restore procedures of public cloud provider
* Costs appear to be MORE, not less than doing it yourself.
- Amazon EBS currently charges $0.10/month/GB, so 1TB == $100.00/mo.
- Current Newegg price for a Seagate Constellation ES ST31000426SS 1TB 7200 RPM SAS 6Gb/s 3.5" Internal Hard Drive with FIPS 140-2 Secure Encryption is approximately $290.00 with shipping.
- Three months of 1 TB Amazon EBS storage costs more than the drive itself!
- This ignores your cost of electricity, but ALSO EXCLUDES Amazon's charges of $0.10 per million IOPs, and monthly CPU rental, which varies depending on CPU power and instance size.
* Choosing to use public clouds is one way management says, "We hate / don't trust our IT department. We'd rather spend a pile of money on an external company than spend some money on training our IT staffers in cloud technology." (This same thought applies to outsourcing.)
* Can be *a* way for your company to afford get by if it's capital-constrained ("I can't afford to BUY a BMW, but I can afford to LEASE one.").
In light of the disadvantages listed above, and the likely-financially-shaky condition of your company if public cloud services are the only thing it can afford, you should probably look for a job elsewhere.