The ransomware attacks raised the need of an appropriate defense, bringing back the mature idea of WORM. Having pre-existing WORM capability in the disk storage alone is not enough for the backup area due to multiple problems like usage complexity, and potential for backup application mishandling of WORM partitions. Instead, integrated WORM support delivered by cooperation of the backup application with the disk storage delivers a complete WORM solution addressing these problems. We present trade-offs and advantages of various integration approaches based on the development of WORM in the NEC HYDRAstor for Veritas NetBackup.