Comment 9 for bug 1079745

The fix above will ignore retcode 0 and 255. My 'isciadm' is returning 21.

2012-12-11 10:39:04 TRACE nova.rpc.amqp File "/opt/common-python/lib/python2.6/site-packages/nova/virt/libvirt/volume.py", line 221, in disconnect_volume
2012-12-11 10:39:04 TRACE nova.rpc.amqp check_exit_code=[0, 255])
2012-12-11 10:39:04 TRACE nova.rpc.amqp File "/opt/common-python/lib/python2.6/site-packages/nova/virt/libvirt/volume.py", line 134, in _iscsiadm_update
2012-12-11 10:39:04 TRACE nova.rpc.amqp return self._run_iscsiadm(iscsi_properties, iscsi_command, **kwargs)
2012-12-11 10:39:04 TRACE nova.rpc.amqp File "/opt/common-python/lib/python2.6/site-packages/nova/virt/libvirt/volume.py", line 125, in _run_iscsiadm
2012-12-11 10:39:04 TRACE nova.rpc.amqp check_exit_code=check_exit_code)
2012-12-11 10:39:04 TRACE nova.rpc.amqp File "/opt/common-python/lib/python2.6/site-packages/nova/utils.py", line 243, in execute
2012-12-11 10:39:04 TRACE nova.rpc.amqp cmd=' '.join(cmd))
2012-12-11 10:39:04 TRACE nova.rpc.amqp ProcessExecutionError: Unexpected error while running command.
2012-12-11 10:39:04 TRACE nova.rpc.amqp Command: sudo /opt/openstack/bin/nova-rootwrap iscsiadm -m node -T iqn.2010-10.org.openstack:vol-00000385 -p 172.30.0.232:3260 --op update -n node.startup -v manual
2012-12-11 10:39:04 TRACE nova.rpc.amqp Exit code: 21
2012-12-11 10:39:04 TRACE nova.rpc.amqp Stdout: ''
2012-12-11 10:39:04 TRACE nova.rpc.amqp Stderr: 'iscsiadm: No records found\n'
2012-12-11 10:39:04 TRACE nova.rpc.amqp

man iscsiadm

       21 ISCSI_ERR_NO_OBJS_FOUND - no records/targets/sessions/portals found to execute operation on.

# rpm -qf /sbin/iscsiadm
iscsi-initiator-utils-6.2.0.872-41.el6.x86_64

Workaround:
Either change [0, 255] to [0, 21, 255] or ignore everything by changing it to range(256).