For those looking for a case of mission-critical services running atop public cloud services, look no further than your iPod or iPad.

A report recently emerged that claimed that Apple is running its new iCloud service using resources from Amazon Web Services and Microsoft Azure, but that Apple has shushed both companies from discussing any of the details.

According to the unnamed source who broke the news to The Register, “Apple is understood to have elected to outsource the plumbing of iCloud because its core competency lies in ‘building great consumer experiences’ and thus it wouldn’t make sense of Apple to become a cloud provider.”

The costs for Apple to build and maintain its own infrastructure to back such a service would have been quite overwhelming. According to The Register, “there’s cost and delay involved in building the infrastructure that iCloud requires, as well as assembling and building the core services. Buildings, power, servers, storage, the recruitment of personnel and having the facility certified would have cost a minimum of $100 million. A more realistic cost for full-scale roll-out could be closer to $1 billion.”

With that said, Apple’s decision makes perfect sense; why not distribute their risk evenly? Aside from the more practical overhead concerns, becoming “hostage” to one provider could prove disastrous if there is an unexpected failure or worse, data breach.

Although Apple might be making use of the two services for now, one has to wonder what is in store for the new expected ten petabyte-capable data center in North Carolina. This could easily accommodate iCloud—and then some, but it remains to be seen just how deep into the cloud business Apple wants to go.

And if Apple does go the way of the cloud—its current partners that are benefitting now from the “unexpected” leak of this information could be wringing their hands later, at least in theory.

This does not come as a surprise to some, as the rumor mill on this subject has been churning away since early summer that Apple’s iCloud was going to make use of the datacenters of others. According to the report, the data from customers and their use of the service will not reside specifically on one cloud service—it will be shuttled back and forth from Microsoft’s Azure to AWS.

This process of moving customer information is called “striping.” As Gavin Clarke explains, “The iCloud data is being striped between the Amazon and Microsoft clouds. That means Apple or Microsoft or Amazon or all three have to implement through the software a way of identifying which user's information is stored in what locations and then to route requests to the correct server.”

The source that informed the original report said that “Microsoft insiders see the iCloud deal as a validation of Azure” with Amazon remaining quiet on that front. Some could argue that if any cloud needs a marketing and visibility boost, it is certainly Redmond’s.

Full story at The Register