On an ONTAP AFF A400 cluster, two relevant storage efficiency technologies are thin provisioning and FlexClone volumes. Thin provisioning allows for more efficient use of storage capacity by allocating it on demand rather than upfront, which helps in maximizing the available space. FlexClone volumes enable instantaneous, space-efficient clones of data, which are very useful in test and development environments, improving overall storage efficiency. Flash Pool and FlashCache are more associated with hybrid and HDD-based systems rather than an all-flash system like the AFF A400.