IBM Z customers have the flexibility to drive business workloads with application servers running on Linux, either natively (bare metal) or with a virtualized environment by employing Kernel-based Virtual Machine (KVM). KVM gained popularity due to the benefit of server deployment flexibility. However, with an extra layer of processing in KVM environments there can be impact to performance and thus a tradeoff between flexibility and performance. IBM Z customers considering KVM need to understand the performance cost of this tradeoff to help determine their workload environments.
The SAP on IBM Z Performance team, in Poughkeepsie, NY, conducted a series of measurements to assess the performance cost of implementing a KVM environment to host SAP application servers. The tests used SAP (SBS 9.0) core banking workloads, with a Db2 database having 100 million banking accounts, which are comparable to some of the largest banks in the world. Tests were conducted that used both banking workload types, Account Settlement (batch) and Day Posting, which simulates online transactional processing (OLTP). They were executed on an IBM z15 with 16 and 32 Integrated Facility for Linux (IFL) processor configurations, that used various degrees of virtualization.
Measurements conducted in this study were performance stress test in nature and not certified benchmarks. Results of the batch and interactive measurements used here are not generally assumed for all possible workloads and environments without verification.
Version 1.01 updates:
- Appendix A added to cover differences with a prior publication on z/VM. The two studies had a lot of differences, Appendix A details the differences.
- Virtualization clarifications were added.
IBM Z; RHEL; KVM; Linux; SAP
22 April 2022