Topics Tab

The Topics tab provides a comprehensive view of all topics in the migration scope, including partition details, replication factors, and selection status.

Topic Statistics

The top section displays aggregate counters:

Metric	Description
Total Topics	Number of topics discovered on the source cluster
Total Partitions	Sum of all partitions across discovered topics
Selected Topics	Number of topics included in the migration
Selected Partitions	Sum of partitions for selected topics

Topic Table

A searchable table lists every discovered topic with the following columns:

Column	Description
Topic Name	Fully qualified topic name. Selected topics display a “Selected” badge next to the name.
Partition Count	Number of partitions for the topic
Replication Factor	Number of replicas configured on the source cluster

Use the search bar to filter topics by name.

Phantom Lag

Phantom lag occurs when Kafka deletes older messages due to retention policies, creating offset gaps between the source and destination clusters. The suite distinguishes between two types of lag:

Lag Type	Description
Real Lag	Messages that exist on the source and have not yet been replicated to the destination
Phantom Lag	Messages that no longer exist on the source due to retention policy deletion

The system calculates the actual lag by excluding phantom lag from the total offset difference. This ensures that topics where all available messages have been replicated display an “In Sync” status, even if the raw offset numbers differ.

Tip

Phantom lag is expected in long-running migrations where source topics have aggressive retention policies. The suite automatically accounts for this, so an “In Sync” status reflects accurate replication of all available data.

Caution

If you observe large phantom lag values, verify that your source cluster retention policies are configured as expected. Unexpectedly high phantom lag may indicate retention settings that are too aggressive for your migration timeline.