Created attachment 552444 [details]
logs

Description of problem:

logging into a lun that is already a part of a domain should be blocked by backend, but I was able several times to add the same lun to two different domains which were apart of the same Data Center. 

Version-Release number of selected component (if applicable):

vdsm-4.9.2-0.65.gitf945dc2.fc16.x86_64
libvirt-0.9.6-4.fc16.x86_64
ovirt-engine-backend-3.0.0_0001-7.fc16.x86_64

How reproducible:

randomly

Steps to Reproduce:
1. create several iscsi luns
2. add a domain using 3 luns
3. add a second domain using other luns+1 or 2 of the target luns used in previous domain. 
  
Actual results:

you will randomaly be able to add the same target to two different domains (sharing the same DC)

Expected results:

we should not be able to even see the targets in the target tab but if we do operation should fail. 

Additional info: full logs