Attaching an iso storage domain fails with "Exception: IRSGenericException: IRSErrorException: IRSNoMasterDomainException: Cannot find master domain"

Issue

• There is an iso domain in unattached status in the environment. Trying to attach to a DC which is in active state fails with below error message.

• In rhevm.log:

2012-11-14 09:20:03,511 ERROR [org.ovirt.engine.core.vdsbroker.irsbroker.IrsBrokerCommand] (pool-19-thread-50) IrsBroker::Failed::AttachStorageDomainVDS

2012-11-14 09:20:03,511 ERROR [org.ovirt.engine.core.vdsbroker.irsbroker.IrsBrokerCommand] (pool-19-thread-50) Exception: IRSGenericException: IRSErrorException: IRSNoMasterDomainException: Cannot find master domain: 'spUUID=426bb3f6-2af3-11e2-879d-00145e36327e, msdUUID=None'

2012-11-14 09:20:03,518 WARN  [org.ovirt.engine.core.bll.storage.ReconstructMasterDomainCommand] (pool-19-thread-50) CanDoAction of action ReconstructMasterDomain failed. Reasons:VAR__ACTION__RECONSTRUCT_MASTER,VAR__TYPE__STORAGE__DOMAIN,ACTION_TYPE_FAILED_STORAGE_DOMAIN_STATUS

• In vdsm.log:

Thread-127::ERROR::2012-11-14 09:14:08,764::task::868::TaskManager.Task::(_setError) Unexpected error
  70361 Traceback (most recent call last):
  70362   File "/usr/share/vdsm/storage/task.py", line 876, in _run
  70363     return fn(*args, **kargs)
  70364   File "/usr/share/vdsm/storage/spm.py", line 115, in run
  70365     return self.func(*args, **kwargs)
  70366   File "/usr/share/vdsm/storage/spm.py", line 1078, in public_attachStorageDomain
  70367     pool.refresh()
  70368   File "/usr/share/vdsm/storage/sp.py", line 912, in refresh
  70369     self.__rebuild(msdUUID=msdUUID, masterVersion=masterVersion)
  70370   File "/usr/share/vdsm/storage/sp.py", line 842, in __rebuild
  70371     self.masterDomain = self.getMasterDomain(msdUUID=msdUUID, masterVersion=masterVersion)
  70372   File "/usr/share/vdsm/storage/sp.py", line 1150, in getMasterDomain
  70373     raise se.StoragePoolMasterNotFound(self.spUUID, msdUUID)
  70374 StoragePoolMasterNotFound: Cannot find master domain: 'spUUID=426bb3f6-2af3-11e2-879d-00145e36327e, msdUUID=None'