A computer-implemented method, according to one embodiment, includes: detecting that a configuration change for a virtualization layer in a multi-tiered data storage system has been received, and determining whether the configuration change corresponds to a tiering adjustment. In response to determining that the configuration change corresponds to a tiering adjustment, I/O pattern changes are predicted. Moreover, a determination is made as to whether each specific extent is stored in a tier of the multi-tiered data storage system suitable to satisfy the predicted I/O pattern changes which correspond to the respective specific extent. In response to determining that one of the specific extents is stored in a tier of the multi-tiered data storage system which is not suitable to satisfy the predicted I/O pattern changes, the at least one specific extent is migrated to another one of the tiers determined as being suitable to satisfy the predicted I/O pattern changes.