In one aspect of the present description, a primary-secondary role swap operation which swaps roles of primary and secondary data storage systems in a distributed data storage system, is synchronized with safe data commit scan operations of individual data storage systems. The safe data commit scan operations of the individual data storage systems are also synchronized to ensure completion of the safe data commit scans and to reduce the occurrence of reductions in input/output (I/O) response times prior to initiation of a primary-secondary role swap operation. Other features and aspects may be realized, depending upon the particular application.