Colors of Noise

Now that Debian Installer supports Xen guests (many thanks to the d-i team for that) it was about time that virtinst/virt-manager could make use of it. Debian's virtinst package in experimental now supports this (the patch is also already included in upstream's mercurial repository). To install a paravirtialized guest on an existing block device use:

virt-install -n xenfoo1 -r 96 --disk path=/dev/blockdevice,device=disk --location=http://people.debian.org/~joeyh/d-i

To install into an image file you additionally have to specify the file size in GB:

virt-install -n xenfoo1 -r 96 --disk path=/path/to/file,device=disk,size=1 --location=http://people.debian.org/~joeyh/d-i

if you don't want to use a sparse file also add sparse=false. In all cases the disk will become /dev/xvda in the domU and the device will be partitioned during installation (so no need to pass in single partitions, booting will happen using pygrub).

--location above points to the Debian Installer daily builds since there hasn't been a d-i release with Xen support yet (this should happen really soon now). Once this has happened you can use any Debian mirror to install. (--location=http://ftp.nl.debian.org/debian/dists/testing/main/installer-i386).

The libvirt munin plugins improved quiet a bit since their initial release:

• I added two more plugins:
  • libvirt-cputime: monitor cpu time used by virtual machines
  • libvirt-mem: monitor the amount of memory used by virtual machines
• these two plugins have adjustable limits for their warning and critical values, see the README for more details
• the plugins now work properly with Xen by special casing Domain-0
• they also ship as a Debian package

Since it should be obvious at a glance when the ticket is about to expire I added a third icon:

It gets shown together with the first notification, which is tunable via the /apps/krb5-auth-dialog/prompt_minutes gconf key:

gconftool-2 --type=int --set /apps/krb5-auth-dialog/prompt_minutes 30

The code landed on the pkinit branch so the build instructions stay the same. I also added a gconf schema to ease configuration and fixed a possible segfault on startup.

My top three remaining "annoyances" in libvirt when it comes to KVM are:

1. missing hotplug for disks
2. daemon restart kills VMs
3. missing migration support

Since KVM now supports PCI hotadd since a couple of releases I fixed up 1 today. I already sent a partial patch for 2 some time ago which I need to finish and clean up. Hopefully 3 is resolved upstream until then.

Once this is done libvirt plus kvm will be a great tandem for virtualization. On the desktop virt-manager does a great job while for H/A purposes it integrates with Redhat's cluster suite - you can use the vm.sh resource script for this after removing the xen specific code and replacing it with calls to ''virsh''.

Here are two munin plugins that monitor disk and network I/O of virtual machines using libvirt. These are also two simple examples on using the libvirt python bindings. You need python-libvirt and python-libxml2 installed in order to use them. If you don't want to use the default uri, try:

[libvirt-*]
env.uri qemu:///system

Munin-node needs to have read access to libvirt's socket. This is the case in Debian's default installation.

There's now a swirlberry package available for the Freerunner:

    echo <<EOF >/etc/apt.conf.d/99_swirlberry.list
    deb http://honk.sigxcpu.org/projects/swirlberry/ unstable/
    EOF
    apt-get install swirlberry

This brings all the necessary dependencies and sets up your X-session. It makes most of the configuration steps superflous, only thing left is setting up your kerberos principal and your tmut accounts. Make sure you restart your zhone-session once after installing the package.

Also make sure that:

hostname --fqdn

returns a valid hostname (if it doesn't check /etc/hosts and /etc/hostname) and that you have something like ntpdate installed for proper timekeeping. Note: if you want to use network manager you still have to add allow-hotplug eth0 in /etc/network/interfaces.