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IBM announced that KVM for IBM z will be withdrawn, effective March 31, 2018.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

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.

Tuesday, January 24, 2017

QEMU v2.8 & libvirt v3.0 released

QEMU v2.8 and libvirt v3.0 (available for download here) are out! The highlight from a KVM on z perspective is the introduction of CPU models.
The CPU models are of primary use in live migration scenarios. For example, in a setup with different z Systems machine generations, it is now possible to check up-front whether the target host will support all facilities required by a guest for a successful migration. In case any of the required facilities are missing, the migration is aborted, and the guest will continue to run on the current host.
Furthermore, a guest can be defined with a backlevel CPU model compatible with the target machine (of a previous z Systems generation), so that migrations become possible.

To see what CPU models QEMU (and hence the host) supports, use virsh domcapabilities:

  $ virsh domcapabilities

      <mode name='custom' supported='yes'>
        <model usable='unknown'>z10EC-base</model>
        <model usable='unknown'>z9EC-base</model>
        <model usable='unknown'>z196.2-base</model>
        <model usable='unknown'>z900-base</model>
        <model usable='unknown'>z990</model>
        <model usable='unknown'>z900.2-base</model>
        <model usable='unknown'>host</model>
        <model usable='unknown'>z900.3</model>
        <model usable='unknown'>z114</model>
        <model usable='unknown'>z890-base</model>
        <model usable='unknown'>z13.2-base</model>
        <model usable='unknown'>zEC12.2</model>

Monday, December 12, 2016

libvirt v.2.5.0 released

libvirt v2.5.0 is now available for download here.
A highlight for the z Systems platform support in this release is scsi_host hostdev passthrough, improving throughput by providing a libvirt frontend for scsi_host devices.

Wednesday, November 16, 2016

New White Paper available: KVM Network Performance

A new white paper has been published: KVM Network Performance - Best Practices and Tuning Recommendations. It is available here, and explores different system configurations (running KVM guests), different networking configuration choices, as well as tuning recommendations for the KVM host and KVM guest environments to achieve greater network performance on the IBM z Systems platforms.

Tuesday, November 15, 2016

New Books available

Two new books are available as follows:
  • The new book KVM Virtual Server Management Tools is available here, covering the open source package virt-manager (see screenshot above) along with its supporting tools virt-install and virt-clone in a generic manner. I.e. it applies to both, KVM on z in general as well as the KVM for IBM z Systems product.
  • The Device Drivers, Features, and Commands for Linux as a KVM Guest book is now also available in a version specific to Ubuntu 16.04 here.
For a publications overview see here.