May 25, 2012 
For all Amazon’s scalability, the offerings can be a bit rigid. For example, you can rent an Amazon instance with a certain amount of storage and compute power, but adding a few gigabytes of memory or another processor might require buying a whole separate instance, which may have more resources than you really need.
“You can’t go to the public cloud and say I want another 64GB of memory here. They look at you and say ‘buy another instance of this type,’” Leinwand said.
Leinwand said the Amazon instance model leads to over-subscription, meaning you end up buying more storage than necessary. Internally, Zynga uses direct-attached storage striped across multiple servers, providing a big I/O performance boost and more efficient utilization, he said.
(Full Story: How Amazon saved Zynga’s butt—and why Zynga built a cloud of its own | Ars Technica)
