HP LTO 4 SCSI, LTO 4 FC, LTO 4 SAS manual

	Flag	Type	Set	Recommended Host Message		Cause
51	Tape directory	W		The tape directory on the tape		An error has occurred
	invalid at			cartridge just unloaded has been		preventing the tape directory
	unload			corrupted. File search performance		being updated on unload.
				will be degraded. The tape directory
				can be rebuilt by reading all the
				data.
52	Tape system	C		The tape just unloaded could not		Write errors occurred while
	area write			write its system area successfully:		writing the system area on
	failure			1.	Copy the data to another tape	unload.
					cartridge.
				2.	Discard the old cartridge.
53	Tape system	C		The tape system area could not be		Read errors occurred while
	area read			read successfully at load time.		reading the system area on
	failure			Copy the data to another tape		load.
				cartridge.
54	No start of data	C		The start of data could not be found		The tape has been
				on the tape:		damaged, bulk erased, or is
				1.	Check that you are using the	of an incorrect format.
					correct format tape.
				2.	Discard the tape or return the
					tape to your supplier.
55	Loading failure	C		The operation has failed because the		The drive is unable to load
				media cannot be loaded and		the cassette and thread the
				threaded.		tape.
				1.	Remove the cartridge, inspect it
					as specified in the product
					manual, and retry the operation.
				2.	If the problem persists, call the
					tape drive supplier’s help line.
56	Unrecoverable	C		The operation has failed because the		The drive is unable to
	load failure			tape cannot be unloaded:		unload the tape.
				1.	Do not attempt to extract the tape
					cartridge.
				2.	Call the tape driver supplier’s
					help line.

HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 85 HP restricted