Change the memory in a running VM

[moussa854]

Is your feature request related to a problem? Please describe.
In XO, in order to change the memory, the VM need to be stopped.

But becaue Pfsense supplies the IP addresses for all VMs including the XO and the host, stopping Pfsense VM will make the system not functioning.

On the other hand, in XCP center I would get a messsage that the memory will change after a reboot.

It would be nice if XO allow a memory change in a running VM by forcing the VM to reboot

[olivierlambert]

I wonder, how XO could send the memory modification if the router VM is off? I wonder what XenCenter is doing 🤔

[julien-f]

I don't know how XenCenter is doing it, XO is not preventing changing the memory, simply translating the error:

xen-orchestra/packages/xo-server/src/xapi/mixins/vm.mjs

Lines 351 to 356 in e3f5799

	return this.call('VM.set_memory_dynamic_range', $ref, dynamicMin, dynamicMax)::pCatch(
	isMemoryConstraintError,
	() => {
	throw new Error('Cannot change memory on running VM')
	}
	)

[olivierlambert]

It seems to be the XC code @julien-f :

        protected override void Run()
        {
            // If either of the static memories has changed, we need to shut down the VM
            // before and reboot afterwards. The user has already been warned about this.
            bool reboot = needReboot;
            XenAPI.Host vmHost = null;
            if (reboot)
            {
                vmHost = VM.Home();
                AsyncAction action = null;
                if (VM.allowed_operations.Contains(XenAPI.vm_operations.clean_shutdown))
                    action = new VMCleanShutdown(VM);
                else
                    action = new VMHardShutdown(VM);
                action.RunExternal(Session);
            }

            // Now save the memory settings. We can't use VM.SaveChanges() for this,
            // because we have to do the operations simultaneously or we will
            // violate the memory ordering constraints.
            try
            {
                if (staticChanged)
                    XenAPI.VM.set_memory_limits(Session, VM.opaque_ref, static_min, static_max, dynamic_min, dynamic_max);
                else
                    XenAPI.VM.set_memory_dynamic_range(Session, VM.opaque_ref, dynamic_min, dynamic_max);
            }

            // Reboot the VM, even if we failed to change the memory settings
            finally
            {
                if (reboot)
                {
                    var action = new VMStartOnAction(VM, vmHost, _warningDialogHAInvalidConfig, _startDiagnosticForm);
                    action.RunExternal(Session);
                }
            }

            Description = string.Format(Messages.ACTION_CHANGE_MEMORY_SETTINGS_DONE, VM.Name());
        }

[julien-f]

Oh I see, my bad I misunderstood, we could detect this error on the UI side and then reboot the VM to change the values.

It should be easy to do.

[olivierlambert]

So todo: do the same approach than XenCenter for now: provide a modal with the error message and tell we can apply after a reboot. Then:

1. Shutdown the VM
2. Set the memory
3. Start the VM

[olivierlambert]

Issue planned for Bastien