>Do you actually keep 2 copy storage pool? One offsite and on onsite?

Mauro - Yes.  That's customary with ADSM customers.
        "Offsite" usually means at a facility geographically distant
from the computer site in case of earthquake or typhoon.  Another
building on campus would be much too close to be effective for
disaster safety.  It takes a day or more for disaster storage site
tapes to come back in a non-disaster situation, hence the need for
a local copypool for more expeditious recoveries of failed primary
pool tapes.  ADSMv3 provides electronic vaulting, which can make
things a lot more convenient.
    Richard