Recommendations for scaling the Workflow Server and its dedicated SQL Server
You can perform any of the following types of configurations during installation of Workflow Solution or upgrade to Workflow Solution :
An on-box configuration is when you install the SQL Server locally on the Workflow Server. Installing the SQL database locally does not result in maximum performance, but it can deliver acceptable performance.
An off-box configuration is when you install the SQL Server on a separate server from the Workflow Server. In such case, the SQL Server performs much better, because the SQL Server offloads the work of data processing and frees resources for Workflow Server processing.
Table: Principal Workflow and SQL Server components for scaling the Workflow environment