Hi Kobi, moving your question to the mailing list, the right place for technical questions.

I have a problem with some FC lun that from some reason when I tried to add it as SD I got: Are you sure? This operation might be unrecoverable and destructive! The following LUNs are already in use - 3600a09803830447a4f244c465759506a Approve operation

after I check the "approve operation" I got:

Operation Canceled Error while executing action New SAN Storage Domain: Cannot create Volume Group

Do you have any suggestions on how to clean it to be able to add it to the engine?

This LUN probably has a partition table because it was used as a direct LUN in a previous test. You can check this with lsblk. You need to wipe it manually using "wipefs -a". Nir