An aspect includes protecting a former primary volume in a synchronous replication relationship. A swap between a primary volume at a first site and a secondary volume at a second site is initiated such that the secondary volume becomes a new primary volume and the primary volume becomes the former primary volume. A fenced state is set as active for the former primary volume. The former primary volume is configured as a fenced volume based on the fenced state being active. Read and write access to the fenced volume is blocked while the fenced state is active.