[RHEV] Why is it not possible to change the name of few VMs while they are running?

Issue

• It is possible to change the name of few virtual machines while they are in running state. But it is not possible to change it for a few.
• Below messages are logged when this fails:

2013-05-22 16:20:04,486 INFO  [org.ovirt.engine.core.bll.UpdateVmCommand] (ajp-/127.0.0.1:8702-8) [428b03eb] Lock Acquired to object EngineLock [exclusiveLocks= key: vm_1 value: VM_NAME, sharedLocks= ]
2013-05-22 16:20:04,488 WARN  [org.ovirt.engine.core.compat.backendcompat.PropertyInfo] (ajp-/127.0.0.1:8702-8) Unable to get value of property: isQuotaDefault for class org.ovirt.engine.core.common.businessentities.VmStatic
2013-05-22 16:20:04,489 WARN  [org.ovirt.engine.core.compat.backendcompat.PropertyInfo] (ajp-/127.0.0.1:8702-8) Unable to get value of property: isQuotaDefault for class org.ovirt.engine.core.common.businessentities.VmStatic
2013-05-22 16:20:04,489 WARN  [org.ovirt.engine.core.compat.backendcompat.PropertyInfo] (ajp-/127.0.0.1:8702-8) Unable to get value of property: managedDeviceMap for class org.ovirt.engine.core.common.businessentities.VmStatic
2013-05-22 16:20:04,489 WARN  [org.ovirt.engine.core.compat.backendcompat.PropertyInfo] (ajp-/127.0.0.1:8702-8) Unable to get value of property: managedDeviceMap for class org.ovirt.engine.core.common.businessentities.VmStatic
2013-05-22 16:20:04,489 ERROR [org.ovirt.engine.core.utils.ObjectIdentityChecker] (ajp-/127.0.0.1:8702-8) [428b03eb] Field time_zone can not be updated when status is Up
2013-05-22 16:20:04,489 WARN  [org.ovirt.engine.core.utils.ObjectIdentityChecker] (ajp-/127.0.0.1:8702-8) [428b03eb] ObjectIdentityChecker.IsUpdateValid:: Not updatable field 'time_zone' was updated
2013-05-22 16:20:04,489 WARN  [org.ovirt.engine.core.bll.UpdateVmCommand] (ajp-/127.0.0.1:8702-8) [428b03eb] CanDoAction of action UpdateVm failed. Reasons:VAR__ACTION__UPDATE,VAR__TYPE__VM,VM_CANNOT_UPDATE_ILLEGAL_FIELD
2013-05-22 16:20:04,489 INFO  [org.ovirt.engine.core.bll.UpdateVmCommand] (ajp-/127.0.0.1:8702-8) [428b03eb] Lock freed to object EngineLock [exclusiveLocks= key: vm_1 value: VM_NAME, sharedLocks= ]