[one-users] How-to set RAM on Running KVM VM in CentOS 6.2x86 + openNebula v3.6

Wed Aug 22 02:06:05 PDT 2012

Hello,

There is a more pratical and fast way:
- open virt-manager and click for VM details
- shutdown VM on OpenNebula
- change RAM and CPU on virt-manager, it will update libvirt xml correctly
- restart machine on OpenNebula

The only catch is that OpenNebula doesn't know about this change and can
overcommit resources.

--
André Monteiro

On Wed, Aug 22, 2012 at 8:17 AM, cloud.b.lab <cloud.b.lab at zoho.com> wrote:

> **
> Junix,
>
> *There is an indirect method*, *but I do not recommend that as it will
> send wrong and incorrect signals to OpenNebula Monitoring program and if
> you do not have fast hands, your VM will end up in "unkn" state.*
>
> Again I am saying I it is not a  recommend practice and you don't try  it
> in a non test environment.
>
>
> If you would like to try it for information purpose , do the following:
>
> 1. Create a test vm and login.
>    e.g.   153 oneadmin oneadmin centos63  runn   10   *1024M* onehost
>  0d 00h12
>
> 2. Verify the total memory using "free" command
>
> 3. Go to the machine running libvirt [means your OpenNebula Node]
>
> 4. Get the doamin ID using                     virsh list
>
> 5. Get a xmldump of running domain         virsh dumpxml <Domain-ID>
>  <file-name>
>     e.g.  virsh dumpxml 7 > /var/lib/one/template/one-149
>
> 6. Open the XML and change the memory values, Save. Assume currently it
> is 1048576.
>   <memory>2095104</memory>
>   <currentMemory>2095104</currentMemory>
>
> 7. Destroy the running domain                 virsh destroy 6
>
> 8. List all doamins in Shut-off state          virsh list --all
>
> 9. If it is there in shut-off state, undefine it          virsh undefine
> <DOAMIn-NAME>
>       e.g. virsh undefine one-149
>
> 10. Recreate the doamin using the XML
>       e.g. virsh create /var/lib/one/template/one-149
>
> 11. Connect through VNC , login as root and check with "free". You will
> see a higher MEM value
>
> 11. Give onevm top ,Wait for some time: OpenNebula reports the following.
>
> 153 oneadmin oneadmin  centos63   runn    5      *2G* onehost      0d
> 00h24
>
>
>  Thanks and regards,
> Anil Kumar
>
>
>
> ---- On Tue, 21 Aug 2012 22:38:39 -0700 *cloud.b.lab<cloud.b.lab at zoho.com>
> * wrote ----
>
> As per my limited understanding:
>
> The  RAM size you specify in the VM template using "MEMORY=xxxx"
> translates to "Maximum available memory" for an active domain.
> Hence, while the domain being active , I think one cannot go beyond the
> available/max mem.
>
> If you edit the XML file through libvirt and force change the Maximum
> memory value to anything higher, you may end up in Kernel Panic situation.
>
> If you would like to try it , do the following:
> 1. Create a test vm
> 2. Verify the total memory using "free" command
> 3. Go to the machine running libvirt
> 4. Get the doamin ID using                               virsh list
> 5. Save the current state of doamin using          virsh save <Doamin_ID>
>  <Filename-with-domain-name>
>     (so that you have a copy of it)
> 6. Restore the doamin      using                        virsh
>  <Filename-with-domain-name>
> 5. Edit the doamin XML using                            virsh edit
> <DOMAIN_ID>
> 6. Try to change values for <memory> and <currentMemory> tags to a higher
> value divisible by 1024.
>      Assume current <memory> is 1048576.
> e.g.
>  <memory>2095104</memory>
>   <currentMemory>2095104</currentMemory>
> 7. Try to reboot the doamin                              virsh reboot
> <DOAMIn-ID>
> 8. Check available memory using "free"
> 9. Try issue setmaxmem command to increase memory to 2095104   virsh
> setmaxmem <DOAMIn-ID> 2095104
>
> oneadmin at onehost:~$ virsh setmaxmem 4 2095104
> error: Unable to change MaxMemorySize
> error: Requested operation is not valid: cannot resize the maximum memory
> on an active domain
> 10. Try to increase available memory
> oneadmin at onehost:~$ virsh setmem 4 2095104
> error: Requested memory size 2095104 kb is larger than maximum of 1048576
> kb
>
> Hope this helps.....
>
> Regards,
> Anil.
>
>
>
> ---- On Tue, 21 Aug 2012 10:42:41 -0700 *Lawrence Chiong<junix88 at gmail.com
> >* wrote ----
>
> Hello,
>
> Can anyone guide me a step-by-step guide on HOWTO change/update RAM on a
> fly / running VM (KVM). Because I tried changing my VM template (in
> sunstone)  its Memory (e.g. from 2048M to 4096M) and then reboot my KVM VM
> but changes made doesn't take effect. So I tried manually changed the
> .../deployment.0 file and update the Memory element and update also the
> vm_pool table on body field +Memory element to 4096M then I restarted
> "oned" + "sunstone" so with mysqld BUT still the memory being updated
> doesn't changed.
>
> Any help is very much appreciated.
>
> Thank you.
>
> Junix
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