13.3. Optimizing libvirt daemons
The libvirt virtualization suite works as a management layer for the RHEL hypervisor, and your libvirt configuration significantly impacts your virtualization host. Notably, RHEL 9 contains two different types of libvirt daemons, monolithic or modular, and which type of daemons you use affects how granularly you can configure individual virtualization drivers.
13.3.1. Types of libvirt daemons
RHEL 9 supports the following libvirt daemon types:
- Monolithic libvirt
The traditional
libvirtdaemon,libvirtd, controls a wide variety of virtualization drivers, using a single configuration file -/etc/libvirt/libvirtd.conf.As such,
libvirtdallows for centralized hypervisor configuration, but may use system resources inefficiently. Therefore,libvirtdwill become unsupported in a future major release of RHEL.However, if you updated to RHEL 9 from RHEL 8, your host still uses
libvirtdby default.- Modular libvirt
Newly introduced in RHEL 9, modular
libvirtprovides a specific daemon for each virtualization driver. These include the following:- virtqemud - A primary daemon for hypervisor management
- virtinterfaced - A secondary daemon for host NIC management
- virtnetworkd - A secondary daemon for virtual network management
- virtnodedevd - A secondary daemon for host physical device management
- virtnwfilterd - A secondary daemon for host firewall management
- virtsecretd - A secondary daemon for host secret management
- virtstoraged - A secondary daemon for storage management
Each of the daemons has a separate configuration file - for example
/etc/libvirt/virtqemud.conf. As such, modularlibvirtdaemons provide better options for fine-tuninglibvirtresource management.If you performed a fresh install of RHEL 9, modular
libvirtis configured by default.
Prochaines étapes
-
If your RHEL 9 uses
libvirtd, Red Hat recommends switching to modular daemons. For instructions, see Enabling modular libvirt daemons.
13.3.2. Enabling modular libvirt daemons
In RHEL 9, the libvirt library uses modular daemons that handle individual virtualization driver sets on your host. For example, the virtqemud daemon handles QEMU drivers.
If you performed a fresh install of a RHEL 9 host, your hypervisor uses modular libvirt daemons by default. However, if you upgraded your host from RHEL 8 to RHEL 9, your hypervisor uses the monolithic libvirtd daemon, which is the default in RHEL 8.
If that is the case, Red Hat recommends enabling the modular libvirt daemons instead, because they provide better options for fine-tuning libvirt resource management. In addition, libvirtd will become unsupported in a future major release of RHEL.
Conditions préalables
Your hypervisor is using the monolithic
libvirtdservice.# systemctl is-active libvirtd.service activeIf this command displays
active, you are usinglibvirtd.- Your virtual machines are shut down.
Procédure
Stop
libvirtdand its sockets.# systemctl stop libvirtd.service # systemctl stop libvirtd{,-ro,-admin,-tcp,-tls}.socket
Disable
libvirtdto prevent it from starting on boot.$ systemctl disable libvirtd.service $ systemctl disable libvirtd{,-ro,-admin,-tcp,-tls}.socket
Enable the modular
libvirtdaemons.# for drv in qemu interface network nodedev nwfilter secret storage; do systemctl unmask virt${drv}d.service; systemctl unmask virt${drv}d{,-ro,-admin}.socket; systemctl enable virt${drv}d.service; systemctl enable virt${drv}d{,-ro,-admin}.socket; doneStart the sockets for the modular daemons.
# for drv in qemu network nodedev nwfilter secret storage; do systemctl start virt${drv}d{,-ro,-admin}.socket; doneOptional: If you require connecting to your host from remote hosts, enable and start the virtualization proxy daemon.
Check whether the
libvirtd-tls.socketservice is enabled on your system.# cat /etc/libvirt/libvirt.conf | grep listen_tls listen_tls = 0If
libvirtd-tls.socketis not enabled (listen_tls = 0), activatevirtproxydas follows:# systemctl unmask virtproxyd.service # systemctl unmask virtproxyd{,-ro,-admin}.socket # systemctl enable virtproxyd.service # systemctl enable virtproxyd{,-ro,-admin}.socket # systemctl start virtproxyd{,-ro,-admin}.socket
If
libvirtd-tls.socketis enabled (listen_tls = 1), activatevirtproxydas follows:# systemctl unmask virtproxyd.service # systemctl unmask virtproxyd{,-ro,-admin,-tls}.socket # systemctl enable virtproxyd.service # systemctl enable virtproxyd{,-ro,-admin,-tls}.socket # systemctl start virtproxyd{,-ro,-admin,-tls}.socket
To enable the TLS socket of
virtproxyd, your host must have TLS certificates configured to work withlibvirt. For more information, see the Upstream libvirt documentation.
Vérification
Activate the enabled virtualization daemons.
# virsh uri qemu:///systemVerify that your host is using the
virtqemudmodular daemon.# systemctl is-active virtqemud.service activeIf the status is
active, you have successfully enabled modularlibvirtdaemons.
