3.4. Red Hat OpenStack Platform 12 Maintenance Release 20 August 2018

These release notes highlight technology preview items, recommended practices, known issues, and deprecated functionality to be taken into consideration when deploying this release of Red Hat OpenStack Platform.

3.4.1. Enhancements

This release of Red Hat OpenStack Platform features the following enhancements:
This update helps operators locate log files after an upgrade from a non-containerized to a containerized deployment.

If old log files are present when the upgrade begins, the old files are moved to a new file location. A readme.txt file is placed in the old file location. The file points to the new log file location.

For example, if a /var/log/nova directory exists, a /var/log/nova/readme.txt file is created, advising the reader to look in the /var/log/containers/nova directory instead.
This update prevents CPU pinning mismatches during Nova live migrations.

Prior to the update, the scheduler did not check whether the guest CPU pinning configuration was supported on the host. A mismatch of CPU pinning caused errors during bootup of the the host. This failed scenario could be repeated over a series of potential hosts.

A new condition in the NUMATopologyFilter filter identifies hosts with proper CPU pinning capability. If no suitable hosts are available, the migration fails quickly with an error message.
This change allows TripleO to deploy Cinder with a Dell EMC VNX backend.
Cinder volume migration between different availability zones is now supported.
Keystone user passwords generated by Heat resources such as WaitConditionHandle now meet more stringent regular expression-based password complexity requirements. The new passwords are 32-character random strings containing at least one uppercase and one lowercase letter, one digit, and one of the characters '!@#%^&*'. These passwords should pass the standard of virtually any regular expression-based password validation.

Previously, generated passwords took the form of 32 hexadecimal digits, and thus never contained uppercase letters or special characters.
Virtual CPUs (vCPUs) can be preempted by the hypervisor kernel thread even with strong partitioning in place (isolcpus, tuned). Preemptions are not frequent, a few per second, but with 256 descriptors per virtio queue, just one preemption of the vCPU can lead to packet drop, because the 256 slots are filled during the preemption. This is the case for network functions virtualization (NFV) VMs in which the per queue packet rate is above 1 Mpps (1 million packets per second).

This release supports two new tunable options: 'rx_queue_size' and 'tx_queue_size'. Use these options to configure the RX queue size and TX queue size of virtio NICs, respectively, to reduce packet drop.
Nova's libvirt driver now allows the specification of granular CPU feature flags when configuring CPU models.

One benefit of this change is the alleviation of a performance degradation that has been experienced on guests running with certain Intel-based virtual CPU models after application of the "Meltdown" CVE fixes. This guest performance impact is reduced by exposing the CPU feature flag 'PCID' ("Process-Context ID") to the *guest* CPU, assuming that the PCID flag is available in the physical hardware itself.

For more details, refer to the  documentation of ``[libvirt]/cpu_model_extra_flags`` in the ``nova.conf`` file for usage details.

3.4.2. Release Notes

This section outlines important details about the release, including recommended practices and notable changes to Red Hat OpenStack Platform. You must take this information into account to ensure the best possible outcomes for your deployment.
To reduce the time spent processing security group updates in the L2 agent, conntrack deletion is now performed in a set of worker threads instead of in the main agent thread.
A new configuration option called bridge_mac_table_size has been added for the neutron OVS agent. This value is set on every Open vSwitch bridge managed by the openvswitch-neutron-agent. The value controls the maximum number of MAC addresses that can be learned on a bridge. The default value for this new option is 50,000, which should be enough for most systems. Values outside a reasonable range (10 to 1,000,000) might be overridden by Open vSwitch.

3.4.3. Known Issues

These known issues exist in Red Hat OpenStack Platform at this time:
You must manually discover the latest Docker image tags for current container images that are stored in Red Hat Satellite. For more information, see the Red Hat Satellite documentation: https://access.redhat.com/documentation/en-us/red_hat_satellite/6.2/html/content_management_guide/managing_container_images#managing_container_images_with_docker_tags