ner, who owns one or more services in the mesh.</p></li></ul><p>Prior to version 1.7, Istio required the control plane to run in one of the <span class=term data-title="Primary Cluster" data-body='<p>A primary cluster is a <a href="/docs/reference/glossary/#cluster">cluster</a> with a
<a href="/docs/reference/glossary/#control-plane">control plane</a>. A single
<a href="/docs/reference/glossary/#service-mesh">mesh</a> can have more than
one primary cluster for HA or to reduce latency. Primary clusters can a