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Re: Unit libvirtd.service could not be found. on VM

On 5/12/20 1:41 PM, Dana Elfassy wrote:
if I understand correctly then I shouldn't have installed libvirt-daemon on the guests VMs?

Just a little background to Daniel's response. Libvirt and QEMU treat guests as black boxes, to some extent. There are some exceptions to this rule, when it comes to para-virtualization (that is when the guest knows it is running virtualized and therefore can optimize some things). The perfect example is virtio (which are para-virtualized devices like NIC, disk, etc.). Depending on the guest the virtio drivers are either already installed (majority of Linux distributions including CentOS, if not all of them) or they have to be installed separately (Windows is typical example).

Then, some tasks can be performed only if there is a small program running inside the guest (so called guest agent), which listens for incoming commands, executes them and sends the result back to libvirt. In CentOS this is qemu-guest-agent RPM. As mentioned, guest agent needs a channel to talk to libvirt which can be configured through virsh directly [1], or in virt-manager (if not already present, but I guess virt-install adds it automatically): Add hardware -> Channel -> Name: org.qemu.guest_agent.0 -> Finish.

Some management applications have their own guest agents (e.g. libguestfs), but I wouldn't worry about them - the management application will configure them automatically; and you are not using them anyway.

However, on the host the set of packages needed is different (note, you don't need any virtio drivers - they are contained in qemu already; nor you need the guest agent). libvirt-daemon-driver-qemu is the package containing qemu driver for libvirt. However, in order to use other features libvirt provides I suggest installing 'libvirt-daemon-kvm' which drags in the rest of packages (e.g. storage driver, network driver, etc.)

The host is also where you need libvirtd running (systemctl enable libvirtd.service or if you want to use socket activation then: systemctl enable libvirtd.socket)


1: https://wiki.libvirt.org/page/Qemu_guest_agent

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