On Tue, Feb 21, 2017 at 10:19 AM, Gianluca Cecchi <gianluca.cecchi@gmail.com> wrote:
Hello,
currently I have a cluster of 3 hosts where each one has FC SAN connectivity to 4 LUNs: 3 are already configured as storage domains (1TB, 2TB, 4TB), one is free, not allocated.
See here for screenshot:

At the moment the command "multipath -l" run on hosts shows all the 4 LUNs.

Now I want to do 2 things at storage array level:

- remove the 2TB storage domain LUN
- remove the 20Gb LUN not yet allocated

What is the correct workflow, supposing I have already emptied the 2TB from VM disks ad such?
Select 2Tb SD, then Datacenter subtab, then "maintenance", detach" and at the end "remove"? 

Yes, these should be your first steps.
 
I think I continue to see 4 LUNs at this point, correct?

Yes.
 
Now I proceed with removal of lun at storage array level?

Should I select an SD line and then "Scan disks" to see refresh the SAN and see in multipath only 2 of them at the end?
Or any manual command at host level before removal from array?

After removing the storage domains you should be able to remove the luns.  I am not extremely familiar with the multipath and low-level scsi commands but I would try the scan disks button and if the luns are not gone from your host you can manually remove them.  I think that involves removing the device from multipath (multipath -d) and deleting it from the scsi subsystem.

Thanks in advance

Hope this helped you.