Computer environments without virtualisation are not possible anymore. Theoretically all problems in this are should be solved by now. There are is an exception:
Running OpenBSD as a guest under KVM, unfortunately gives some headaches. ⇒SEPPmail, our preferred mail encryption gateway, is a prominent example. It was running for years without problems. It has no problems under VMware, neither as appliance. As a KVM guest it started to behave badly.
2 countermeasures are required to make it run smooth again:
The configuration of the virtual machine in ⇒Proxmox:
boot: c bootdisk: virtio0 cores: 1 hotplug: 0 memory: 4096 name: <hostname> net0: virtio=<mac-addresse>,bridge=vmbr0,tag=3 numa: 0 ostype: other scsihw: virtio-scsi-pci serial0: socket smbios1: uuid=<uuid> sockets: 1 tablet: 0 vga: serial0 virtio0: ceph:<disk>,size=30G
Important are sockets: 1 and serial0: socket.
Using a VGA console, the CPU starts using 100% and the machine freezes. Use a serial console as the solution for this problem.
On current Proxmox versions, the synchronisation of the time does not work anymore.
Running the command:
time sleep 1
I expect a duration of 1 second. Not so with OpenBSD and KVM (Proxmox). After a few hours uptime the duration of this command takes several seconds. After a reboot everything is fine for a short time period.
This problem can be solved:
On the host system (Proxmox) you execute the command:
echo options kvm-intel preemption_timer=N >>/etc/modprobe.d/kvm-intel.conf
Reboot the host system.
Then check the values:
If it returns “N”, the problem is solved.
It seems, on later versions of KVM, at least the ones used in Proxmox 6.4 and 7, this setting is no longer required.