What’s Happening in OpenStack-Ansible (WHOA) – June 2016

The world of OpenStack moves quickly. Each day brings new features, new bug fixes, and new ways of thinking. The OpenStack-Ansible community strives to understand these changes and make them easier for operators to implement. The OpenStack-Ansible project is a collection of playbooks and roles written by operators for operators. These playbooks make it easier to deploy, maintain, and upgrade an OpenStack cloud. Keeping up with the changes in the OpenStack-Ansible project is challenging.

Xen 4.5 crashes during boot on Fedora 22

If you’re currently running a Xen hypervisor on a Fedora release before 22, stay put for now. There’s a bug in Xen when you compile it with GCC 5 that will cause your system to get an error during bootup. In my case, I’m sometimes getting the crash shortly after the hypervisor to dom0 kernel handoff and sometimes it’s happening later in the boot process closer to when I’d expect a login screen to appear.

Xen’s XSA-108 patch and Fedora

Xen’s latest vulnerability, XSA-108, has generated a lot of buzz over the last week. Most of the attention has come from the reboot notifications from large cloud providers (including my employer). The vulnerability allows a user within a guest to potentially read memory from another guest or the hypervisor itself. The window of available memory is small but it could be read many times over - much like how the Heartbleed vulnerability was exploited.

Performance benchmarks: KVM vs. Xen

After having some interesting discussions last week around KVM and Xen performance improvements over the past years, I decided to do a little research on my own. The last complete set of benchmarks I could find were from the Phoronix Haswell tests in 2013. There were some other benchmarks from 2011 but those were hotly debated due to the Xen patches headed into kernel 3.0. The 2011 tests had a good list of benchmarks and I’ve done my best to replicate that list here three years later.

Configure remote syslog for XenServer via the command line

Citrix has some helpful documentation online about configuring remote syslog support for XenServer using the XenCenter GUI. However, if you need to do this via configuration management or scripts, using a GUI isn’t an option. Getting it done via the command line is relatively easy: HOSTUUID=xe host-list --minimal SYSLOGHOST=syslog.example.com xe host-param-set uuid=${HOSTUUID} logging:syslog_destination=${SYSLOGHOST} xe host-syslog-reconfigure host-uuid=${HOSTUUID} Removing the configuration and going back to only local logging is easy as well: