Snapshot Replication Agent Test

The Snapshot Agent run at the Distributor and is typically used with all types of replication. It prepares schema and initial data files of published tables and other objects, stores the snapshot files, and records information about synchronization in the distribution database.

The first step towards troubleshooting a delay in database replication is to figure out at which step of the replication process the delay occurred, and which agent performed that step. Using the Snapshot Replication Agent test, you can determine whether/not the Snapshot agent is contributing to a slowdown (if any) in the replication process. This test, at pre-configured intervals, monitors how quickly the agent delivers transactions to the distribution database. Latencies in creation of snapshot files or in recording synchronization details in the Distributor are thus revealed.

This test is disabled by default. To enable this test, go to the enable / disable tests page using the menu sequence : Agents -> Tests -> Enable/Disable, pick Microsoft SQL as the Component type, Performance as the Test type, choose a ‘replication test’ from the disabled tests list, and click on the << button to move the test to the ENABLED TESTS list. Finally, click the Update button.

Target of the test : A Microsoft SQL server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the Microsoft SQL server being monitored

  1. TEST PERIOD - How often should the test be executed
  2. Host – The IP address of the Microsoft SQL server.
  3. Port - The port number through which the Microsoft SQL server communicates. The default port is 1433.
  4. instance – The name of a specific Microsoft SQL instance to be monitored. The default value of this parameter is “default”. To monitor an Microsoft SQL instance named “CFS”, enter this as the value of the “instance” parameter.
  5. ISPASSIVE – If the value chosen is yes, then the Microsoft SQL server under consideration is a passive server in a SQL cluster. No alerts will be generated if the server is not running. Measures will be reported as “Not applicable" by the agent if the server is not up.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Commands Delivered:

 

Indicates the rate at which the Snapshot agent delivered commands to the Distributor.

Commands/Sec

 

Transactions Delivered:

Indicates the rate at which the Snapshot agent delivered transactions to the Distributor.

Trans/Sec

A high value is desired for this measure. If the value of this measure dips consistently over time, it is indicative of a slowdown.

A contention for memory / CPU resources on the SQL server, or high disk I/O on the server could cause snapshotting to slow down.