Microsoft® SQL Server 2012 Unleashed

Distributed Transactions

Typically, transaction management controls only the data modifications made within a single SQL Server instance. However, the increasing interest and implementation of distributed systems brings up the need to access and modify data distributed across multiple SQL Server instances within a single unit of work.

What if in the banking example, the checking accounts reside on one SQL Server instance and the savings accounts on another? Moving money from one account to another would require updates to two separate SQL Server instances. How do you modify data on two different instances and still treat it as a single unit of work? You need some way to ensure that the distributed transaction retains the same ACID properties ...