OVIRT engile unable to import old "Export storage": How to fix

WARNING: before to start this tests, backup your datacenters,storages, config files etc..!!!
 
After reinstall ovirt 3.5.x I got following error during the import export domain:
Error while executing action: Cannot add Storage Connection. Storage connection already exists.

This was due to the many experiments what I was doing with old storage, I was trying  to attach or detach/ destroy them in meanwhile the name server went down, so Ovirt-Engine  somehow was screwed out.

Not show time to fix the corrupted database:
1) Try identify ovirt storageconnections using API:
curl -k -v -u "admin@internal:xxxxxxx" -H "Content-type: application/xml" -X GET https://ovirt-engine.cls/api/storageconnections

It shows something like this:

.....

   
       

192.168.101.102

        nfs
        /tank/VMs/EXPORT
   

......


2) So let us delete it:
 curl -k -v -u "admin@internal:xxxxx"  -X DELETE https://ovirt-engine.cls/api/storageconnections/8e5335e0-8821-40ee-8dc8-6b4245032920

 output will be like this:
complete

Important to have here complete, otherwise you should dive more deeper to find out the trouble.

So next try to connect again your old export, if it claims that domain is inuse with other one then make following:
1) mount old export storage to /tmp/media
2) find file: dom_md/metadata
3) remove line _SHA_CKSUM=
4) set empty  POOL_UUID=

Try to import in to new DC.
Enjoy the new setup.