Let’s be honest, many customers really love the stretched farm architecture because they can achieve high availability and disaster recovery at the same time (even if it is not a perfect DR solution).
Some enterprises have data centers that are located in close proximity to one another, connected by high-bandwidth fiber optic links. When this environment is available it is possible to configure the two data centers as a single farm. This distributed farm topology is called a “stretched” farm.
When SharePoint 2013 shipped a few months ago, the bad news was that stretched farm was not supported anymore.
The good news is that it this now supported if the follow prerequisites are met :
- There is a highly consistent intra-farm latency of <1ms (one way), 99.9% of the time over a period of ten minutes. (Intra-farm latency is commonly defined as the latency between the front-end web servers and the database servers.)
- The bandwidth speed must be at least 1 gigabit per second.
More details here.
Data tiers of stretched farms can alos be protected with technologies like SQL Server 2012/2014 Always on Availability groups as I illustrated in this post.