A first storage controller includes a first processor, a first memory, and a first switch having a first port. A second storage controller includes a second processor, a second memory, and a second switch having a second port. A storage system connects the first port and the second port by a first link. The first processor and the first switch are connected by a second link configured to transfer user data and a third link configured to transfer control data. The second processor and the second switch are connected by a fourth link configured to transfer user data and a fifth link configured to transfer control data. The first port and the second port transfer the control data in preference to the user data on the first link.