The relationship between the hypervisor and its Linux kernel allows it to run on a dual design, unifying the host and hypervisor modes. Red Hat Enterprise Linux supports multiple virtualization use cases, allowing customers to choose when and where to use virtualization. By leveraging the Linux operating system, KVM virtualization overhead is minimized, but not to the detriment of performance. The Red Hat Enterprise Linux 6.3 release also supports up to the leading 160 virtual CPUs per virtual machine, allowing even large workloads to be virtualized.
These tests, run on the Red Hat and IBM technology combination described above, have demonstrated that enterprise workloads can be efficiently migrated into a virtualized environment while still delivering high performance results. The KVM host server, consisting of an IBM System x3850 X5 with four Intel Xeon® E7-4870 processors (sockets) and 256 GB of memory, ran on a storage back-end capable of delivering at 1.4 million IOPS.
Single and multiple virtual machines were tested, using Red Hat Enterprise Linux 6.3 on all guests and on the host. Both reads and writes were included in the test workload in order to more accurately simulate the demands of an enterprise workload. Using only four guests, KVM was able to achieve up to 1.4 million IOPS for random I/O requests of 8KB in size and more than 1.6 million for random requests of 4KB in size. The KVM performance matched the physical operating system performance of this setup and KVM was bounded by the test storage back-end performance. Using a single guest, KVM was able to achieve about 800,000 IOPS for random I/O requests of 8KB in size, and more than 900,000 IOPS for random requests of 4 KB or less. It should be noted that VMware recently indicated that it could achieve one million IOPS for a single host running six virtual machines running on a vSphere™ 5.0 host.1
Average latency rates for both tests remained low and constant across different I/O request sizes, demonstrating that block I/O performance on KVM can remain predictable, even with a changing number of guests. As the number of guests and I/O requests increases, block I/O performance on the KVM hypervisor is able to scale to match demand load.
Red Hat Enterprise Virtualization for Desktops and Servers is the first enterprise-ready, fully open source virtualization platform. Red Hat Enterprise Virtualization offers industry-leading performance and scalability for real-world enterprise applications including Oracle, SAP and Microsoft Exchange, and includes enterprise virtualization management features such as live migration, high availability, load balancing and power saving. Because Red Hat Enterprise Virtualization is available through Red Hat’s software subscription model, users benefit from lower acquisition ownership costs for the same or better feature set when compared to other solutions. The platform recently entered beta for its upcoming 3.1 release.
Because Red Hat Enterprise Virtualization and Red Hat Enterprise Linux incorporate the same KVM hypervisor, those systems using Red Hat Enterprise Virtualization are gaining the same virtualization technology that achieved the top performance posted by the Red Hat Enterprise Linux KVM and IBM systems used for this performance trial.