It happens that it works somehow strangely, and then it turns out that this is the effect of a lack of RAM for service needs.

We go via SSH to AHV and look for a running CVM there:

virsh list --all | grep CVM

Let’s see how much is there now:

virsh dumpxml <cvm_name> | grep -i "memory"

According to the CVM standard, it is created with 16Gb. This is enough for a small load. But we need to increase it to 32Gb.

All over the Internet they write that you first need to turn it off, and then increase it. But experimentally, when working with KVM, a slightly different way was found - first we increase it and then distort the CVM.

Increase to 32Gb:

virsh setmaxmem <cvm_name> --config --size 32GiB
virsh setmem <cvm_name> --config --size 32GiB

Next we turn it off:

virsh shutdown <cvm_name>

We wait about a minute so as not to break anything - the automation should work and switch all VMs to neighboring CVMs.

And let’s start:

virsh start <cvm_name>

Actually that’s all. Open Prism and fly on.

p.s. During a restart, CVM will disappear from Prism until a complete restart.