RE: Ultrium 4 Tape Initialization

[rob@xxxxxxxxx]

No, as far as your backup is concerned CLEAR(*NO) does not "leave data" on 
the tape.

Technical details:  When you execute a DLTF does it leave the data on the 
disk?  Yes.  But the file name is gone.  It will eventually be written 
over.  Back on the S/36 there was on option on it's equivalent of DLTF 
that would actually write binary zeros throughout all the space previously 
consumed by the file.  This is what CLEAR(*YES) is doing, writing binary 
zeros throughout the entire tape.  Useful for security purposes and to 
really write on the tape to see if it may be "bad".  But on a nightly 
basis you do not need to run CLEAR(*YES).  You will still have all the 
tape space available if you run CLEAR(*NO).  Basically it wiped out the 
header and goes from there.  Trust me, it just works.  We've been doing 
this for decades.


Rob Berendt