The Microsoft SQL Server Distributed Replay feature helps you assess the impact of future SQL Server upgrades. You can also use it to help assess the impact of hardware and operating system upgrades, and SQL Server tuning. Similar to SQL Server Profiler, you can use Distributed Replay to replay a captured trace against an upgraded test environment.

Unlike SQL Server Profiler, Distributed Replay is not limited to replaying the workload from a single computer. Distributed Replay offers a more scalable solution than SQL Server Profiler. With Distributed Replay, you can replay a workload from multiple computers and better simulate a mission-critical workload.

The Microsoft SQL Server Distributed Replay feature can use multiple computers to replay trace data and simulate a mission-critical workload. Use Distributed Replay for application compatibility testing, performance testing, or capacity planning.

But before we get there we need to look at risk. Do not run it against your production environment. ONLY use DRU in a test environment as it:

  • Can be a security risk to sensitive information
  • Only uses Windows Authentication
  • Only supports the SQL Server Native Client ODBC data access provider

What is distributed Replay functionality in SQL Server 2012?

  • It was introduced in SQL 2012
  • Allows us to assess SQL, OS and hardware upgrades
  • Allows us to do Performance tuning or troubleshooting
  • DRU can run in 2 modes—Synchronization or Stress mode

Distributed Concepts

  • Distributed Replay administration tool: A console application, DReplay.exe, used to communicate with the distributed replay controller. Use the administration tool to control the distributed replay.
  • Distributed Replay controller: A computer running the Windows service named SQL Server Distributed Replay controller. The Distributed Replay controller orchestrates the actions of the distributed replay clients. There can only be one controller instance in each Distributed Replay environment.
  • Distributed Replay clients: One or more computers (physical or virtual) running the Windows service named SQL Server Distributed Replay client. The Distributed Replay clients work together to simulate workloads against an instance of SQL Server. There can be one or more clients in each Distributed Replay environment.
  • Target server: An instance of SQL Server that the Distributed Replay clients can use to replay trace data. We recommend that the
  • The Distributed Replay administration tool, controller, and client can be installed on different computers or the same computer. There can be only one instance of the Distributed Replay controller or client service that is running on the same computer.

Distributed Replay Utility

Benefits of Distrbuted Replay Utility (DRU)

  • It is not limited to replaying a Workload on one machine
  • Better simulate mission critical workloads
  • Use Distribution Replay for application compatibility testing, performance testing, or capacity planning.
  • Provides better scalability than profiler as DRU is scalable up to 16 clients
  • The Microsoft SQL Server Distributed Replay feature can use multiple computers to replay trace data and simulate a mission-critical workload. Use Distributed Replay for application compatibility testing, performance testing, or capacity planning.

When to Use the Tools

SQL Server Profiler

  • You want to use the conventional replay mechanism on a single computer. In particular, you need line-by-line debugging capabilities, such as the StepRun to Cursor, and Toggle Breakpoint commands.
  • You want to replay an Analysis Services trace.

Distributed Replay

  • You want to evaluate application compatibility. For example, you want to test SQL Server and operating system upgrade scenarios, hardware upgrades, or index tuning.
  • The concurrency in the captured trace is so high that a single replay client cannot sufficiently simulate it.

For the video on this, please go to the Distribution Replay webinar I did on this for Pragmatic Works.