I found a posting of mine from a previous thread
regarding Apple's data centers. Some very interesting information as well as some links to older articles from Apple Insider.
Apple surely has some massive plans:
Apple buys data center originally built for MCI reported in 2006.
Apple says NC data center will support iTunes and MobileMe this spring and As Carolina data center debut looms, Apple expanding in Silicon Valley too as reported in 2011.
Apple will invest $250M in new Oregon data center reported in 2012.
Apple to invest $1B in Nevada data center, business facilities reported in 2012.
Notably, there is a Rumor: Apple's iCloud to be powered by Microsoft, Amazon servers
"... Apple is said to have outsourced the "plumbing" of iCloud because its "core competence lies in 'building great consumer experiences,' so it didn't make sense for Apple to become a cloud provider," according to Clarke.
Another cited reason for maintaining two providers is that Apple hopes they will be forced to keep up with each other on "reliability, new features, security, and price." The iPhone maker is looking to avoid becoming "hostage" to one supplier..."
"... Sources suggested that iCloud is running on "the full Azure service – the Windows Azure compute and controller part and SQL Azure storage which hosts tables, queues and flat files." User data will reportedly be stored in multiple locations across the three companies' servers. As is to be expected, a multiple-provider hosting solution would come with its own set of challenges, as Apple may have to work across platforms, utilizing custom software to manage requests and keep track of data..."
Futhermore, Apple career postings indicate:
"... position is focused primarily on SUN/Oracle server support with a second focus on IBM/AIX servers. You should also understand SAN, RAID and file system technology (IBM, SUN, Xserve RAID's, etc.)..."