On 12/23/2011 10:14 AM, hero wrote:

hello everyone:

during the days I use kvm,I have got some questions I want to know,please read the following questions.

1.When a kvm VM is running, I use 'virsh setvcpus <domain> <count>' to change the cpu numbers of the VM, and when I use 'virsh dumpxml <domain>',there is a change from '<vcpus>count</vcpus>' to '<vcpus current="currentcount">count</vcpus>', just because of this I can't start the VM after I shutdown it. could you help me about this.

It works well for me, the guest can be successfully started after shutdowning, what's the libvirt version?

2. when I use "virsh setmaxmem <domain> <value>" to change the max memory of the kvm VM, it says "error: Unable to change MaxMemorySize
error: this function is not supported by the connection driver: virDomainSetMaxMemory", I want to know if libvirt has bugs or not.

Also work for me, for a running domain, will meet the following error as expected:

# virsh setmaxmem vr-rhel5u7-x86_64-kvm 1048576
error: Unable to change MaxMemorySize
error: Requested operation is not valid: cannot resize the maximum memory on an active domain

For a inactive domain, original Max memory is 524288 kB, the change is valid:

# virsh dominfo vr-rhel5u7-x86_64-kvm
Id:             -
Name:           vr-rhel5u7-x86_64-kvm
UUID:           663ce18a-e257-2b05-91ae-fe29381b3a2f
OS Type:        hvm
State:          shut off
CPU(s):         3
Max memory:     1048576 kB
Used memory:    524288 kB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: selinux
Security DOI:   0

3.It works fine except I reboot the VM after I use "virsh setmem <domain> <value>" to change the kvm VM boot memory, for example, I change the memory 3000000k, but it can not save the value the next time to reboot.

You should see options family of virsh setmem such as --live, --config and --current:

    --config         affect next boot Note: it is a option what you want.
    --live             affect running domain
    --current       affect current domain

Good Luck!
Alex

Best wishes and Merry Christmas!

SunYongGang


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