Replication Queue Test

As the domain controller formulates change requests, either by a schedule being reached or from a notification, it adds a work item for each request to the end of the queue of pending synchronization requests. Each pending synchronization request represents one <source domain controller, directory partition> pair, such as “synchronize the schema directory partition from DC1,” or “delete the ApplicationX directory partition.”

When a work item has been received into the queue, the domain controller processes the item (begins synchronizing from that source) as soon as the item reaches the front of the queue, and continues until either the destination is fully synchronized with the source domain controller, an error occurs, or the synchronization is pre-empted by a higher-priority operation.

A long replication queue is often an indication that synchronization requests are not swiftly processed by the AD server. If the reasons for the abnormal queue length are not determined quickly and addressed promptly, replication of some changes may be stalled indefinitely causing the source and destination domain controllers to remain ‘out-of-sync’ for long durations; this in turn may result in users having to work with obsolete data! To prevent such an eventuality, you can use this test to continuously track the replication queue length, so that you can be alerted as soon as the number of work items in the queue crosses an acceptable limit. You can also use the detailed diagnostics of this test to know what type of synchronization requests are in queue, so that you can figure out why the requests are taking too long to be processed.

Target of the test : An Active Directory or Domain Controller

Agent deploying the test : An internal agent

Outputs of the test : One set of results for every Active Directory site that is being monitored

Configurable parameters for the test
Parameters Description

Test period

This indicates how often should the test be executed.

Host

The IP address of the machine where the Active Directory is installed.

Port

The port number through which the Active Directory communicates. The default port number is 389.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Replication queue size

Indicates the number of synchronization requests that are currently in the replication queue, awaiting processing.

Number

A high value for this measure is a cause for concern, as it indicates that too many synchronization requests are pending processing. This could be due to a severe processing bottleneck on the AD server. Very short replication schedules and large synchronization requests that require a lot of processing time are also factors that can increase the replication queue length.

You can use the detailed diagnosis of this measure to know which requests are yet to be processed, so that you can figure out why there is a delay (if any) in processing.