+---------------------------+ TM 
	|   |   |   |   |   |   |   |    
	| d | i | g | i | t | a | l |              Interoffice Memorandum
	|   |   |   |   |   |   |   |    
	+---------------------------+    
	
	To: Whom it may concern                    Date:  16 March 1993
                                                Updated:  18 February 1994
	                                           From:  Mickey Lane
	                                           Dept:  Tape Engineering
	                                           Ext.:  237-6151
	                                           Loc.:  SHR3-2/X27
	                                           Net.:  ELWOOD::LANE
	                                              lane@elwood.enet.dec.com
                                                      (508) 841-6151

	Subject:  MLU and unsupported tape drives

          On occasion, MLU rejects operations on a tape drive with the
	error:

	    %MLU-F-DEVUNKWN, device type is not supported

	  This usually occurs because VMS has assigned a generic device
	type to the tape in question. This can be verified by:

            $ show dev $1$mua96/full

	    Magtape $1$MUA96: (HSC007), device type (type not yet identified),
	    is online, controller supports tape data caching (write-back
	    cache disabled), recordoriented device, file-oriented device,
	    served to cluster via TMSCP Server, error logging is enabled.
 
	         Note "device type (type not yet identified)."

	  Tape devices connected the the K.SCSI module in the HSC also
	suffer from this problem as the devices show up as an HST00 or
	HST01.

	  In order for MLU to function, it *must* know what type of device
	it is acting on. A mechanism exists to inform MLU what the device
	type is even if VMS doesn't know.

	  If your MLU installation seems to have this problem, define
	the following logical either manually or in the system startup
	configuration files.

	    $ define/system MLU_$1$MUA96 SA100

	  Note that the logical name is made up of "MLU_" and VMS's name
	for the tape, "$1$MUA96" in this case. This logical must go in the
	system table. The value assigned to the logical can be anything
	from the following (incomplete) table:

            TAD85       TA85       TF86      TF867      HSC_TZ857
            TZ867       SA106      TA86      TA867      HSC_TZ86

	  When MLU finds "device type (type not yet identified)" or device
	type = HST01, it will look for the logical "MLU_device_name." If
	found, it will use the supplied translation in place of what VMS
	is calling the device and start over. If that doesn't work, the
	initial message will be re-issued.

	  Note that tapes connected to the HSC are identified as "HSC_TZ86"
	or "HSC_TLZ06."

	  The TLZ06 device shows up as different things on different
	versions of the operating system. For V5.* versions of VMS,
	the device is a "TLZ6." For V6.* versions (and Alpha), it's a
	"TLZ06." MLU is sensitive to this difference and will reject
	the definition based on VMS versions. Therefor:

	  For VMS 5.*,
             $ DEFINE MLU_<device> TLZ6
	  For VMS 6.*,
             $ DEFINE MLU_<device> TLZ06