Knowledge Series: Managing KVM on IBM Z with oVirt

See here for a new entry in our "knowledge" series, providing step-by-step instructions on how to include IBM Z hosts in an oVirt data center.

Getting Started: RHEL 7.5 Instructions added

Instructions for RHEL7.5 were added to the Getting Started with KVM on Z series.
See here for the actual page.

Ubuntu 18.04 released

Ubuntu Server 18.04 LTS is out! Support for IBM Z is available here.
It ships

• Linux kernel 4.15,
• QEMU v2.11, and
• libvirt v4.0.

As obvious from these package versions, support for IBM z14 is readily in place.

Since this is a so-called LTS (Long Term Support) release providing approx. 5 years of support (in contrast to the usual 9 months of non-LTS releases), it is of particular interest to Ubuntu users interested in a stable environment for production deployments.

QEMU v2.12 released

QEMU v2.12 is out. Here are the highlights from a KVM on Z perspective:

• Added support for an interactive bootloader. As always, we strongly recommend to use the existing support in libvirt.
  To enable/disable, add the following element to your guest definition:
  
     <os>
       <bootmenu enable=’yes|no’ timeout=’n’/>
       ...
     </os>
  
  The timeout parameter specifies a timeout in milliseconds after which the default entry is chosen.
  Alternatively, set attribute loadparm to PROMPT to enable the boot menu without timeout in the respective disk's element:
  
     <disk ...>
       <boot order=’1’ loadparm=’PROMPT’/>
       ...
     </disk>
  
  Example:
  To enable the boot menu for 32 seconds for a guest using a libvirt
  domain XML format follows:
  
     <domain type=’kvm’>
       <os>
         <bootmenu enable=’yes’ timeout=’32000’/>
         ...
       </os>
• Exposure of guest crash information: When a guest is started using libvirt and crashes due to disabled wait, wrong interrupts or a program check loop, libvirt will print the information to the guest’s log, typically located at /var/log/libvirt/qemu.
  E.g. a crash due to a disabled wait results in an entry as follows:
  
     s390: psw-mask=’0xXXXXXXXXXXXXXXXX’, psw-addr=’0xXXXXXXXXXX
           XXXXXX’,crash reason: disabled wait
  
  Requires  libvirt v4.2.
• Added support for guests with more than 8TB of memory.

White Paper: Exploiting HiperSockets in a KVM Environment Using IP Routing with Linux on Z

Our performance group has published a new white paper titled "Exploiting HiperSockets in a KVM Environment Using IP Routing with Linux on Z".
Abstract:

"The IBM Z platforms provide the HiperSockets technology feature for high-speed communications. This paper documents how to set up and configure KVM virtual machines to use HiperSockets with IP routing capabilities of the TCP/IP stack.
It provides a Network Performance comparison between various network configurations and illustrates how HiperSockets can achieve greater performance for many workload types, across a wide range of data-flow patterns, compared with using an OSA 10GbE card."

This white paper is available as .pdf and .html.

RHEL 7.5 with support for KVM on Z available

Red Hat Enterprise Linux 7.5 is out. From the release notes, available here:

Availability across multiple architectures
To further support customer choice in computing architecture, Red Hat Enterprise Linux 7.5 is simultaneously available across all supported architectures, including x86, IBM Power, IBM z Systems, and 64-bit Arm.

Support for IBM Z is available through the kernel-alt package, as indicated earlier here, which provides Linux kernel 4.14. QEMU ships v2.10 via package qemu-kvm-ma, and libvirt is updated to v3.9.0 for all platforms.
Thereby, all IBM z14 features as previously listed here are available.
Check these instructions on how to get started. 

SLES 12 SP3 Updates

SLES 12 SP3, released late last year, received a couple of mostly performance and security-related updates in support of IBM z14 and LinuxONE through the maintenance web updates.
In particular:

• Instruction Execution Protection
• SIMD Extensions
• STHYI Support
• Transparent activation of new hardware features: This will enable a set of performance-oriented hardware facilities of z14 that do not require hypervisor changes.
  This includes the following facilities:
• miscellaneous-instruction-extensions facility 2
• entropy-encoding compression facility
• order-preserving-compression facility