bin/106973: 'tar' cannot read own tape, but 'pax' can

[mjacob at freebsd.org]

The following reply was made to PR bin/106973; it has been noted by GNATS.

From: mjacob at freebsd.org
To: Bernd Luevelsmeyer <bdluevel at heitec.net>
Cc: mjacob at freebsd.org, FreeBSD-gnats-submit at freebsd.org,
        freebsd-bugs at freebsd.org
Subject: Re: bin/106973: 'tar' cannot read own tape, but 'pax' can
Date: Fri, 22 Dec 2006 08:24:37 -0800 (PST)

 I would expect a Travan based drive to be like a QIC tape. From my 
 minimal experience with them, they seem to be derived from QIC standards 
 and probably derive from native QIC-02 starting back 20 odd years ago 
 (like the old Cipher Floppy-Tape drive which had an SA850 interface).
 
 I dunno why tar didn't give a 0 exit on the create, but try again 
 replacing the || with ;
 
 The point here is to try and force 512 and 1024 byte record creation and 
 to force 512 and 1024 byte reads.
 
 >
 > Sure. I would have expected the eotmodel to be 2, but it appears to have
 > been 1 to begin with. In order to keep the mail to a sensible length, I
 > deleted most of tar's output and replaced it with "[...]". However, I
 > don't quite understand the point of this test, since the "tar c" _does_
 > work fine; it's the reading that doesn't work.
 >
 > Script started on Fri Dec 22 10:37:13 2006
 > #mt -f /dev/sa0 seteotmodel 1
 > /dev/sa0: old model was 1 filemark at EOT
 > /dev/sa0: new model  is 1 filemark at EOT
 > #cd /usr/include
 > #tar cvfb /dev/sa0 1 . || tar tvfb /dev/sa0 1
 > a .
 > a a.out.h
 > a ar.h
 > a assert.h
 > a bitstring.h
 > [...1571 lines...]
 > a bsm/audit.h
 > a bsm/audit_kevents.h
 > a bsm/audit_internal.h
 > a bsm/audit_record.h
 > a bsm/audit_uevents.h
 > a bsm/libbsm.h
 > #mt -f /dev/sa0 rewind
 > #tar cvfb /dev/sa0 2 . || tar tvfb /dev/sa0 2
 > a .
 > a a.out.h
 > a ar.h
 > a assert.h
 > a bitstring.h
 > [...1571 lines...]
 > a bsm/audit.h
 > a bsm/audit_kevents.h
 > a bsm/audit_internal.h
 > a bsm/audit_record.h
 > a bsm/audit_uevents.h
 > a bsm/libbsm.h
 > #exit
 >
 > Script done on Fri Dec 22 10:44:49 2006
 >