Scratch pool in NetBackup Administration 7.5

Hello,

I'm new to the NetBackup, need to clarify how the NetBackup working with DataDomain. The DataStore pools have 1140 virtual virtual tapestapes, Scratch pool have 487 virtual tapes, ToRemove pool have 207 virtual tapes. But DataDomain is struggling over a month over 90% full, and yesterday 98% full. My question is, why it did not pull(used) the tapes from Scratch or ToRemove pool ? Does it need a manual intervention to activate these virtual tapes?

Thank you

Regards,

Thirun