After the centos 6.2 update I noticed libvirt was not running on some servers. Looking at the logs I found
Starting libvirtd daemon: 10:35:16.697: 6933: info : libvirt version: 0.9.4, package: 23.el6_2.1 (CentOS BuildSystem <http://bugs.centos.org>, 2011-12-17-16:39:59, c6b4.bsys.dev.centos.org)
10:35:16.697: 6933: error : virNetServerMDNSStart:460 : internal error Failed to create mDNS client: Daemon not running
Further investigation found avahi was needed for this to work. The final fix was running
yum -y install avahi
/sbin/chkconfig messagebus on
/sbin/chkconfig avahi-daemon on
In centos 6.2 restarting libvirt will not restart the vm’s. Once done libvirt was running again.
I have been testing openvz on centos6 today, and following my normal config I installed software raid1. Everything went fine until a reboot into the centos kernel. On a reboot, I got an error
dracut cannot find root, “sleeping forever”
As an old school sysadmin I hate change, what is dracut I’m thinking (not to mention fstab has UUID’s instead of LABELs, looking like ubuntu now). This replaces the old initrd system. Ok it has a shell you can boot into rdshell which seems kind of cool. On to the fix I found.
I noticed that on openvz dracut never assembled raid1. I ran
dracut -f –add-drivers raid1 –mdadmconf /boot/initramfs-2.6.32-042stab024.1.img 2.6.32-042stab024.1
Which at the time was the stable kernel and rebooted. System is back up with out errors.
You may need to run
mdadm –examine –scan
and update your /etc/mdadm.conf file