cinder creating volume raise error

1. I use devstack and default setting
zhu@zrz-dev:~/git/devstack$ cinder create 1
+---------------------+--------------------------------------+
| Property | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| created_at | 2012-10-22T17:10:06.033684 |
| display_description | None |
| display_name | None |
| id | 679d9e62-26f4-4f2c-a3c0-24d5217dc565 |
| metadata | {} |
| size | 1 |
| snapshot_id | None |
| status | creating |
| volume_type | None |
+---------------------+--------------------------------------+
zhu@zrz-dev:~/git/devstack$ cinder list
+--------------------------------------+--------+--------------+------+-------------+-------------+
| ID | Status | Display Name | Size | Volume Type | Attached to |
+--------------------------------------+--------+--------------+------+-------------+-------------+
| 679d9e62-26f4-4f2c-a3c0-24d5217dc565 | error | None | 1 | None | |
+--------------------------------------+--------+--------------+------+-------------+-------------+

cinder-volume log:
2012-10-22 17:10:06 ERROR cinder.volume.iscsi [req-fb047733-dfb0-4a8f-9dfc-7088c6cf4ae7 e9208f4cbdf64e54875a12d2a39709a4 8ef44aaaa2314e8e8061e18637ac05c5] Failed to create iscsi target for volume id:volume-679d9e62-26f4-4f2c-a3c0-24d5217dc565.
2012-10-22 17:10:06 ERROR cinder.openstack.common.rpc.amqp [-] Exception during message handling
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp Traceback (most recent call last):
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/openstack/common/rpc/amqp.py", line 276, in _process_data
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp rval = self.proxy.dispatch(ctxt, version, method, **args)
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/openstack/common/rpc/dispatcher.py", line 145, in dispatch
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp return getattr(proxyobj, method)(ctxt, **kwargs)
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/manager.py", line 163, in create_volume
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp volume_ref['id'], {'status': 'error'})
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp self.gen.next()
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/manager.py", line 156, in create_volume
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp model_update = self.driver.create_export(context, volume_ref)
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/driver.py", line 376, in create_export
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp volume_path)
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/iscsi.py", line 140, in create_iscsi_target
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp raise exception.ISCSITargetCreateFailed(volume_id=vol_id)
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp ISCSITargetCreateFailed: Failed to create iscsi target for volume volume-679d9e62-26f4-4f2c-a3c0-24d5217dc565.
2012-10-22 17:10:06 TRACE cinder.openstack.common.rpc.amqp

2. I add "print e" in cinder/volume/iscsi.py line 137 and try again, it raise the same error and print the detail of exception.

cinder-volume log:
1e18637ac05c5] Failed to create iscsi target for volume id:volume-db1c260b-81a2-4a0c-9e5b-45d537549589.
Unexpected error while running command.
Command: sudo /usr/local/bin/cinder-rootwrap /etc/cinder/rootwrap.conf tgt-admin --update iqn.2010-10.org.openstack:volume-db1c260b-81a2-4a0c-9e5b-45d537549589
Exit code: 2
Stdout: ''
Stderr: 'Config::General The file "/opt/stack/cinder/volumes/*" does not exist within ConfigPath: /etc/tgt! at /usr/sbin/tgt-admin line 172\n'
2012-10-22 17:20:17 ERROR cinder.openstack.common.rpc.amqp [-] Exception during message handling
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp Traceback (most recent call last):
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/openstack/common/rpc/amqp.py", line 276, in _process_data
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp rval = self.proxy.dispatch(ctxt, version, method, **args)
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/openstack/common/rpc/dispatcher.py", line 145, in dispatch
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp return getattr(proxyobj, method)(ctxt, **kwargs)
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/manager.py", line 163, in create_volume
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp volume_ref['id'], {'status': 'error'})
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp self.gen.next()
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/manager.py", line 156, in create_volume
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp model_update = self.driver.create_export(context, volume_ref)
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/driver.py", line 376, in create_export
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp volume_path)
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp File "/opt/stack/cinder/cinder/volume/iscsi.py", line 141, in create_iscsi_target
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp raise exception.ISCSITargetCreateFailed(volume_id=vol_id)
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp ISCSITargetCreateFailed: Failed to create iscsi target for volume volume-db1c260b-81a2-4a0c-9e5b-45d537549589.
2012-10-22 17:20:17 TRACE cinder.openstack.common.rpc.amqp

3. I redo the command
zhu@zrz-dev:/opt/stack/cinder$ sudo /usr/local/bin/cinder-rootwrap /etc/cinder/rootwrap.conf tgt-admin --update iqn.2010-10.org.openstack:volume-db1c260b-81a2-4a0c-9e5b-45d537549589
Config::General The file "/opt/stack/cinder/volumes/*" does not exist within ConfigPath: /etc/tgt! at /usr/sbin/tgt-admin line 172
zhu@zrz-dev:/opt/stack/cinder$