[daip] reading old [sun] tapes on new [linux] system

[Eric Greisen]

joe cammisa writes:
 > hello, eric.
 > 
 > hopefully, this is the "more information" that you asked for.
 > 
 > 1) after starting aips, we use MOUNT and the tape mounts normally.
 > 
 > 2) we set up the inputs for the PRTTP task and upon starting said task, the
 > following shows up on the message server:
 > 
 > URANIA> PRTTP1: ZTPWAT: ERROR   6 FOR LUN = 31 IBUFF = 2 TO TAPE
 > URANIA> PRTTP1: ZERROR: IN ZTPWA2 ERRNO = 5 (Input/output error)
 > URANIA> PRTTP1: ZERROR: IN ZTPWA2 ERRNO = 5 (Input/output error)
 > URANIA> PRTTP1: This usually means you're at END-OF-TAPE

 > URANIA> PRTTP1: Read at least   15.244 Megabytes in    5550 logical records

 > 3) in /var/log/messages we see this:
 > Jun 19 15:49:38 urania kernel: st0: Error with sense data: Info fld=0x1800,
 > Current st09:00: sense key Medium Error
 > Jun 19 15:49:38 urania kernel: Additional sense indicates Medium format
 > corrupted

      These both say rather clearly that there is a parity error on
the tape.  If it is happening on a lot of tapes there may be a head
alignment problem, so that a tape written on machine A may be read
over on A but will have problems on machine B.

If one had the I/O error occurring right at the beginning of the job,
I would worry about AIPS' Z routines or your tape setup - but after 15
Megabytes and a sensible header, I think the tape is reading fine up
to the point about 250 records before the end of the primary data
where a media error occurs.

After the media error something has to reset the drive before aips can
get normal responses to its status inquiries, so I am not suprised
that you had trouble after the abrupt quit.

 > 
 > 4) afterwards, we are unable to use the tape drive in this session of aips;
 > all attempts result in messages like this (in the end we use unix commands to
 > eject the tape):

 > >rewind
 > ZTAP2: error performing null op on tape drive
 > ZTAP2: Input/output error
 > AIPS 1: ZTAPE: LUN 31 IO ERROR AT   1 OP OF REWI/REWI SYS ERR CODE 0000
 > AIPS 1: TAPE PROBLEM
 > >dismount
 > AIPS 1: ZMOUN2: error rewinding/unloading tape drive
 > >

 > by the way, the tape drive does indeed work in aips--they've done lots of
 > reading and writing of aips data over the months; it's only with certain tapes
 > that they see this problem.  originally, i thought it was only with old tapes
 > that the problem occurs, but the tape we were testing with this afternoon is
 > apparently of a much more recent vintage.

     So far as I can tell your problem is with the tapes not with
aips.  I realize that that is not helpful and leave one wondering why
so many errors, but all aips can do is whatever the system tells us
and your log says media error.

Eric Greisen