Servers that support two-phase commit
Updates in a two-phase commit situation are coordinated if they must all commit or all roll back in the same unit of work.
Example
You can update an IMS database and a Db2 table in the same unit of work. Suppose that a system or communication failure occurs between committing the work on IMS and on Db2. In that case, the two programs restore the two systems to a consistent point when activity resumes.
Db2 coordinates commits even when a connection is using one-phase commit in a distributed transaction. In this case, however, only one location can perform an update.