A method of and system for managing a data set of a storage facility is disclosed. The data set may be a sequential-access data set. The method and system may include structuring the sequential-access data set to have a first group-of-records configured for adding a second group-of-records to the sequential-access data set. The method and system add a second group-of-records to the sequential-access data set. The method and system merge the second group-of-records with the first group-of-records in response to a triggering event. The method and system establish, in response to merging the second group-of-records with the first group-of-records, a marker configured to indicate the first and second group-of-records, as merged, is sorted.