z/VM Large Memory: Linux on System z

Both z/VM 5.2 and z/VM 5.3 were able to handle the scenario with a relatively large amount of physical memory (80 GB) and the use of twice as much virtual memory than physically available (memory overcommitment). The usage of z/VM 5.3 and VMRM-CMM is recommended for this type of workload (transactional database workload using asynchronous disk I/O). In the memory overcommitted case, z/VM 5.3 shows significant improvements for performance compared to z/VM 5.2. The features VMRM-CMM and CMMA require that the most current fixes available for these features for Linux and z/VM are installed. Memory overcommitment is expected to cause performance degradation, where VMRMCMM reduces that impact to 13%, which is a very small impact for a memory overcommitment of a factor of two.