Troubleshooting the virtualization layer of OpenStack
KVM is the de facto hypervisor choice for OpenStack compute as service. There are plenty of native KVM debugging mechanisms that you can use for troubleshooting issues that occur while launching an instance on your OpenStack environment. Alternatively, if something unusual suddenly happened with a critical instance, libvirt and QEMU provide a rich set of debugging controls that allow us to query (or modify) the state of virtual machines in distress.
The following log files play a very important role in troubleshooting compute layer issues. Please note these files are on the nova compute hosts nodes:
/var/log/nova/nova-api.log /var/log/nova/nova-compute.log /etc/libvirt/qemu/*.xml /var/lib/nova/instances/* /var/lib/libvirt/qemu/
/var/lib/libvirt/qemu/ is the directory where QEMU creates a log file for each instance or VM that was started on the node. If there is an I/O problem faced by the instance, or storage performance is degraded,...
