Ran into a similar type of issue on the HP/UX platform.  It seems that the
design of the label libv command, whether you specify overwrite yes or no,
ADSM will always attempt to read the media for a label.  In the case of new
media, an I/O error will be generated (from the attempt to read a label that
isn't there).  The process then goes on and labels the media correctly.  I
spoke to IBM about this since in our situation, we generate a Tivoli alert
on tape I/O errors.  They had no resolution (for HP) and indicated that ADSM
was working as designed.  IBM did indicate this was an issue on HP due to
the use of the GENERICTAPE driver, specifically.  Apparently the driver was
not smart enough to distinguish this situation from a real I/O error
(perhaps the NT driver is). My old PMR # was 37925, branch 111.  Hope this
helps.