Nova Compute does not work with symbolic link

Issue

• In grizzly, we used the solution to mount a file system bases on remote iscsi disk volume and create a symbolic link to /var/lib/nova directory. By doing so all the vm instances will be written to the remote iscsi disk so as to leverage on the large capacity of the disk.
  However, with Havana version, we always got permission denied error message when nova compute service works with the symbolic link.

/var/nova/log/compute.log 

2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]     domain.createWithFlags(launch_flags)
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]   File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 187, in doit
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]     result = proxy_call(self._autowrap, f, *args, **kwargs)
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]   File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 147, in proxy_call
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]     rv = execute(f,*args,**kwargs)
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]   File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 76, in tworker
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]     rv = meth(*args,**kwargs)
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]   File "/usr/lib64/python2.6/site-packages/libvirt.py", line 708, in createWithFlags
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]     if ret == -1: raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1] libvirtError: internal error Process exited while reading console log output: qemu-kvm: -chardev file,id=charserial0,path=/var/lib/nova/instances/0ac0f529-1bcf-4c81-b75f-3beb31abe9b1/console.log: Could not open '/var/lib/nova/instances/0ac0f529-1bcf-4c81-b75f-3beb31abe9b1/console.log': Permission denied
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]
2014-03-03 22:42:44.964 3430 TRACE nova.compute.manager [instance: 0ac0f529-1bcf-4c81-b75f-3beb31abe9b1]
2014-03-03 22:42:44.968 3430 DEBUG nova.openstack.common.rpc.amqp [req-2ce2b55c-3bb3-4ecf-be86-2a89f7276a54 ea89dff9a81f4ac1843112749d5e29c5 959eca2553e24acf9d1674c911a1bf2b] Sending compute.instance.create.error on notifications.error notify /usr/lib/python2.6/site-packages/nova/openstack/common/rpc/amqp.py:621
2014-03-03 22:42:44.969 3430 DEBUG nova.openstack.common.rpc.amqp [req-2ce2b55c-3bb3-4ecf-be86-2a89f7276a54 ea89dff9a81f4ac1843112749d5e29c5 959eca2553e24acf9d1674c911a1bf2b] UNIQUE_ID is d55e95d9930942f58abd7c1fbf13fd15. _add_unique_id /usr/lib/python2.6/site-packages/nova/openstack/common/rpc/amqp.py:341