[libvirt-users] /etc/machine-id

[Cristian Ciupitu]

On Saturday, June 21, 2014 5:37 PM, Gene Czarcinski <gczarcinski at gmail.com> wrote:
>
>I was under the impression that the value of /etc/machine-id was unqiue
>for every OS installation on a system.  This seems to be the case on
>real hardware.  That is, if I install Fedora 19, Fedora 20, and
>Fedora-rawhide on a system, they will each have a different value for
>/etc/machine-id.
>
>This does not seem to be the case for qemy-kvm-libvirt virtual systems. 
>SOmetimes they are different but I just noticed that a virtual system
>with both Fedora 20 and Fedora rawhide installed (btrfs partitioning),
>the two installations have the same value in /etc/machine-id.  The two
>installs have different ext4 partitions for /boot, different subvols for
>the respective rootfs and the same/shared subvol for /home.

Maybe this snippet from the systemd-machine-id-setup(1) man page [1]
explains it:

> If run inside a KVM virtual machine and a UUID is passed via the -uuid
> option, this UUID is used to initialize the machine ID instead of a
> randomly generated one. The caller must ensure that the UUID passed is
> sufficiently unique and is different for every booted instanced of the
> VM.

Cheers,
Cristian Ciupitu

[1]: http://www.freedesktop.org/software/systemd/man/systemd-machine-id-setup.html