Wednesday, May 10, 2017

QEMU v2.9 released

QEMU v2.9 is out. Here are the highlights from a KVM on z perspective:
  • Added support for virtio-crypto, providing a virtual crypto device as a front-end to the host's crypto capabilities on z Systems.
  • Added multiqueue support for virtio-ccw devices, improving throughput in presence of multiple processors.
  • Provided network boot enablement. See here for further details.

Tuesday, May 2, 2017

Linux kernel 4.11 released

Linux kernel 4.11 (available here) has been released, improving Kernel Samepage Merging (KSM) support for KVM on z:

KSM is an existing feature of the Linux kernel that allows the kernel to merge pages with identical content, indicated as MADV_MERGEABLE via madvise(), across different processes to save memory.
This z Systems specific extension improves the performance of userspace applications (e.g. QEMU) in case large amounts of empty/zeroed pages are merged.
This feature is disabled by default, enable as follows:

   $ echo 1 > /sys/kernel/mm/ksm/use_zero_pages

Thursday, April 27, 2017

Saturday, April 8, 2017

Webinar: OpenStack for KVM with Ubuntu on IBM z Systems

Abstract: This session is divided into three parts, each with an equal time share of 15-20 minutes. We will start with a recap what Infrastructure as a Service (IaaS) is all about to resolve some minor potential misconceptions. After that, an overview of the most important capabilities of OpenStack are shown. The most common (at least in the past) pain points and mitigations are discussed too. Eventually, after having enough context, we take a look at Ubuntu and OpenStack on z. This includes deployment, operations and supported features. This session will bring you benefit if you're new(-ish) to OpenStack, evaluating IaaS solutions, and care about the user/operators-view.

Speaker : Markus Zoeller, OpenStack Development, IBM Germany

Audience: IT Manager, IT Architects, System Administrators

Date: Wednesday, April 26th, 2017
Time: 11:00 AM EST / New York, 4:00 PM CET / Germany
Duration: 75 minutes

Registration: You can register here. After registering, you will receive a
confirmation email containing information about joining the webinar.

Replay & Archive: All sessions are recorded. For the archive as well as a replay and handout of this session (available by Apr 30, 2017) and all previous webcasts please visit

Contact: Please direct any questions to Stephanie Gherghe at

Tuesday, March 14, 2017

KVM for IBM z Withdrawal

IBM announced that KVM for IBM z will be withdrawn, effective March 31, 2018. From the notice:
"KVM for IBM z Systems Version 1.1.2 will be the last release delivered by IBM. However, IBM will continue to provide the Linux and KVM enablement for z Systems [...]"
Make no mistake: The withdrawal only affects the product KVM for IBM z. It does not mean the end for KVM on z (our open source effort to support KVM on IBM z Systems). To the contrary, development will not only continue unaffected, but the options for users grow, especially with the recent addition of SuSE to the existing support in Ubuntu.
See the FAQ for further details.

SLES now supports KVM on z

SuSE has announced formal support for KVM on z starting with SLES12SP2. See the official announcement here for full details.

Monday, February 13, 2017

Knowledge Series: Choosing the Right Configuration

Large server setups are quite typical for KVM on z. One common pitfall is that system and application defaults that work well for a small number of servers may not work very well for a large number of virtual servers or in combination with huge host resources. The following sections present a list of snags that could happen, along with respective suggestions on how to resolve them.