[Info-vax] Delete a file from a tape?

[Richard B. Gilbert]

Christoph Gartmann wrote:
> Hello,
> 
> I have a tape with a few files (backup savesets). The last file on tape is
> an incomplete saveset. Thus, I would like to delete this last file from the
> tape. But OpenVMS 7.3-2 lists the file, asks for confirmation to delete and
> finally refuses to do so. My next attempt was to recreate the saveset in
> question via BACKUP with /REPLACE. Here I got:
> 
> %BACKUP-F-POSITERR, error positioning MKB200:[000000]13OCT09MAC358.BCK;
> -SYSTEM-F-OPINCOMPL, operation is incomplete
> 
> Thus, how do I get rid of the incomplete saveset on tape without loosing
> the previous savesets? Do I need to copy the contents of the tape to disk,
> delete the incomplete file, initialize the tape and copy back the rest?
> 
> Regards,
>    Christoph Gartmann
> 

There IS NO SUCH OPERATION as "DELETE" on a tape.  The best you can do 
is to overwrite it or degauss the tape.  Degaussing the tape should be a 
last resort with DLT tapes.  If you degauss a DLT tape you may not be 
able to write it again; I think there is some sort of prerecorded track 
on DLT-IV and maybe its successors!  IIRC that prerecorded track 
synchronizes the "write clock" or some such thing.