  Problems reading BACKUP tape (NOTANSI)? 
 The Question is:
 
I have a BACKUP tape (DDS) that was created some time ago on a VAX/VMS 5.5
system.  At the time I had some trouble reading it on an Alpha/VMS 7.2
system - eventually we managed to read it by using some combination of
MOUNT/NOLABEL and BACKUP (according to
 my rough notes).
 
I am now trying to read the *same* tape again on the same Alpha/VMS 7.2
system.  Whatever I try, I get a "not valid ANSI format" error.
 
I've eliminated the possibility that the media is bad by trying several
different tapes.
 
I seem to remember that the problem was related in some way to the fact that
the backup save-set name was not the same as the tape label.
 
Any ideas?
 
 
 The Answer is:
 
  The usual commands to list the contents of the first BACKUP saveset
  found on a tape device -- regardless of the BACKUP saveset name used
  -- are:
 
    $ MOUNT/FOREIGN mkcu:
    $ BACKUP mkcu:/SAVE/LIST
 
  Most DDS media has a lifetime of roughly two thousand head passes --
  the tape reaches its rated lifetime when the tape has passed the head
  two thousand times, usually long before two thousand BACKUP operations.
 
  BACKUP does not have any requirement that the tape label match -- or
  differ from -- the saveset name.  They are entirely unrelated.
 
  This would initially appear to be a problem with the media, or with the
  level of data compression requested/required to read the media.  Given
  the same combination to media and DDS drive reportedly worked before,
  this would thus look more like a media or hardware problem.  If you are
  receiving errors, then the tape is corrupt, the tape drive does not
  support reading the media (differing device compression support?), or
  there is a hardware problem.  (Also remember to check the error log for
  any clues you might find there; using DECevent DIAGNOSE.)
 
  The OpenVMS Wizard would initially suggest cleaning the DDS tape drive.
  Then confirm compatible level of compression is used.  Then try using
  another DDS tape drive, preferably a model similar to the one that
  wrote the DDS tape.  Failing that, contact the drive vendor or your
  local hardware support organization -- problems with certain DDS drives
  are not unheard of.  Failing that, contact the Compaq Customer Support
  Center for assistance.
 
