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Date: Wed, 18 Dec 1996 16:48:39 +0100 (MET)
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Subject: misc/2242: mt blocksize 512 in Release 2.1.6 install
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>Number:         2242
>Category:       misc
>Synopsis:       Suggest add optional   mt blocksize 512   to install
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Wed Dec 18 08:00:01 PST 1996
>Last-Modified:
>Originator:     Julian Stacey jhs@freebsd.org
>Organization:
Julian
---
Julian H. Stacey	jhs@freebsd.org		http://www.freebsd.org/~jhs/
>Release:        2.1.6
>Environment:

Release 2.1.6

>Description:

Maybe we could have provision for a command of form
        mt blocksize 512
in the install ?

During install of Release 2.1.6 ...

I have a
        (aha0:2:0): "TANDBERG  TDC 3800 =04Y" type 1 removable SCSI 2
        st0(aha0:2:0): Sequential-Access density code 0x0,  drive empty
& it's running in start stop mode (non streaming) during an install,
just like it does when I don't do an
        mt blocksize 512
after new media insertion, in normal use on a normal installed fbsd sys.

The non streaming behaviour could be rather disconcerting for a non FreeBSD
person as the screen just shows "Attempting to extract from SCSI tape drive"
and it sounds more like it repeatedly failing & not streaming,
till one hits Alt F2 & sees signs of successful extraction.

BTW after the install I validated the tape on another TANDBERG  TDC 3800 =04Y
on the other system that wrote the tape, & it exhibited the same
behaviour there too,
        tar t
ran in lurch mode then ctrl C &
        mt blocksize 512
        tar t
then it streamed.
Thus the tape was confirmed to be in correct 512 fixed block format
(if it had streamed straight off before the 
	mt blocksize 512
that would have indicated the tape was in vari sized blocking, I think)

When one generates distrib tapes for others, one has to assume
fixed 512 blocking type of drives as least common denominator,
& if I create one of those, & recipient has (unknown to me)
an enhanced drive like mine,  it won't stream during install.

>How-To-Repeat:
>Fix:

Adding an optional
	mt blocksize 512
to the tape menu would solve this ... if there's space on the flop :-)

Julian
---
Julian H. Stacey        jhs@freebsd.org         http://www.freebsd.org/~jhs/
>Audit-Trail:
>Unformatted: