zfcp.63f95d <bus ID of the zfcp device>: Registering
unit 0x<LUN> on port 0x<WWPN> failed
Explanation
The Linux kernel
could not allocate enough memory to register the SCSI device at the
indicated LUN with the SCSI stack. The SCSI device is not available.
User response
Free some memory then detach the LUN and attach
it again.