We got a new IBM FlashSystem 840 the other day, and I was hooking it up to one of our systems on some spare fiber ports for testing. I created a couple of luns and shared them to the server, and ran rescan-scsi-bus.sh to see the new luns. It saw all the luns, but out of the two, only one was mapping to a device, both an sd device and a multipath device.
In trying to track down why, came across a couple of Red Hat articles on why. The following commands were useful:
lsscsi -g sg_map -x
This article https://access.redhat.com/solutions/53023 says that the lun was being used by something else, and the tables aren’t really cleared. The only way to really fix it is to reboot. So I guess that is what I’m doing.