IBM’s mainframe and POWER-based virtualization technologies have achieved one of the computer industry’s most stringent security certifications. IBM’s virtualization technology used by its servers to run multiple operating systems simultaneously. The mainframe logical partitioning technology received a Level 5 rating. IBM System z9 EC logical partitioned (LPAR) has been tested by an independent evaluator. IBM POWER microprocessors are used in IBM System p and System i servers as well as IBM’s TotalStorage DS8000 storage systems.”]
Source: https://www.darkreading.com/attacks-breaches/ibm-tech-certified