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Mirror between regions

Rename the regions of a two-region sandbox and choose how each mirror link copies records, with MirrorMaker 2 or with offset-preserving Cluster Linking.

How-to guides 8 of 10

3 min read

Updated 19 October 2026

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The two-region sandboxes start with MirrorMaker 2 links between fixed regions. The region and mirror-link editor renames the regions and sets, link by link, whether records cross by MirrorMaker 2 or by Cluster Linking.

Before you start

Steps

1. Open the editor

Select the primary region band. The Inspector’s Shape tab holds regions · free play and mirror links · free play, after cluster · free play and racks · free play. The cluster’s own view, opened by selecting the cluster frame, has the same tabs.

A region or link edit rebuilds the sandbox from its start and drops the records and actions recorded so far. So it waits in the plan at the bottom of the Inspector, which lists the changes, until you select Apply.

2. Rename the regions

Under regions · free play, the region 1 and region 2 fields hold the region names. Change primary to us and select Apply: the sandbox rebuilds with a us region, and its mirror copy in the second region is now called us.orders. A two-region sandbox always keeps exactly two regions.

3. Pick the replication kind

Under mirror links · free play, each row is one link: the source region, the target region, and the kind, MirrorMaker 2 or Cluster Link. Set the kind to Cluster Link. A ↔ reverse checkbox appears next to it: ticking it also creates the link in the opposite direction, dormant until you switch over. remove deletes a link, and Add mirror link adds one when a source and target pair is still free. Each of these edits joins the plan; select Apply once you are done.

Select the arrow between the regions. The mirror link’s kind reads Cluster Link (offset-preserving), and its destination is marked · read-only mirror. The DR posture card on the Why tab now reads “Active-passive · Cluster Linking (offset-preserving)”, with “clean switchover” as the RTO and a Cluster Link · offset-preserving line that names the direction records flow in, us → dr.

5. Promote or switch over

Open the Failure tab. In Failover (DR), the link’s row has two Cluster Linking controls:

  • promote mirror · us.orders turns the mirror into a writable topic and stops mirroring it. In Confluent Platform the cluster link stays up for its other mirror topics; in the simulator a link carries this one topic, so the link is removed with it;
  • switch over · us.orders promotes the mirror and reverses the link in place, so the original topic becomes the read-only mirror. Run it again on the reversed link to switch back.

After a switchover, the link’s direction row shows the reversed direction, marked reversed (switched over). Because a Cluster Link keeps offsets, a consumer that moves to the promoted topic resumes at the same offsets, with no translation.

On the Active / active sandbox, the first edit in either section replaces its two region-owned topics with one shared orders topic, mirrored along the links you define.