From:	EVMS::RLORD        "Rick Lord DTN 381-1438"  8-JAN-1997 09:14:49.78
To:	LENNY, TOM_C
CC:	SUE, MARY, GLENN,RLORD
Subj:	Minimally tested Exabyte 8200 fix available - Rick


								8-Jan-96
								Wednesday

	Hi,

	The following fix appears to provide V7.0 level access to the Exabyte
	8200 tape drive, but in testing it I came upon a sort of strange
	failure. The fix simply involves clearing the whole mode parameter
	header when doing a MODE SELECT instead of leaving the block size as
	read from the device. This is consistent with what's been done in
	MKDRIVER for as long as I know of, so my guess is that it was just a
	porting oversight. Diffs are at the end of this message. It might be
	a good idea to retest a bunch of the apparently non-busted tapes with
	this driver, but it really is doing exactly what V7.0 did, which is
	clear the whole mode parameter header unconditionally.

	Now, the weird error:

	In V7.0, when I try to do a Backup to a Files-11 mounted tape drive
	(I know, probably no one in the real world cares about this, but I
	figured I'd try it anyway, if only for that reason), it fails with
	this error:

	$ Backup /Verify /Log /Label=F11 *.com mkb500:Test.BCK /Save
	%BACKUP-F-MOUNTFOR, MKB500:[SYSMGR]TEST.BCK; must be mounted /FOREIGN

	In V7.1, the same command results in BACKUP exiting with SS$_ACCVIO
	after copying what would be the last file of the wildcarded file spec:

	%SYSTEM-F-ACCVIO, access violation, reason mask=00, 
	virtual address=00000028, PC=00000000, PSL=00000000

	The bad status appears to be generated by BACKUP - I checked the status
	codes (port and class) of the last 64 commands returned from MKDRIVER
	and they're all good.

	I looked through the BACKUP facility, and it looks to me like there
	have been some changes in TAPEUTIL that could result in a failure like
	this - but I haven't verified or QAR'd it since I'm really not sure if
	this is something we want to encourage.

	- Rick

	p.s. Glenn, I have VAX V7.0 and V7.1 drivers if you want to try them

************
File WORK204:[RLORD.TMP.V71]MODE_SENSE_COMMON.MAR;5
 1171   CLRQ	SCSI$MPBD$B_BLOCK(R2)		; Clear 8 bytes at once
 1172   INCL	R0				; Increment to next block
******
File WORK204:[RLORD.TMP.V71]MODE_SENSE_COMMON.V71;1
 1171   CLRL	SCSI$MPBD$B_BLOCK(R2)		; Clear 4 bytes at once
 1172   INCL	R0				; Increment to next block
************

Number of difference sections found: 1
Number of difference records found: 1

DIFFERENCES /IGNORE=()/MERGED=1/OUTPUT=WORK204:[RLORD.TMP.V71]Z.;1-
    WORK204:[RLORD.TMP.V71]MODE_SENSE_COMMON.MAR;5-
    WORK204:[RLORD.TMP.V71]MODE_SENSE_COMMON.V71;1

