Hi Kevin,
As RAC implies, the only *sure* way is to totally restore a system with it. Not a very practical method, huh?
What I do is create TWO tapes & then check them both by:
1) mt rew #rewind the tape - if it's not /dev/rmt/0mn, you'll need -f /dev/rmt/Xmn where X=instance number
2) mt fsf 1 #This skips one file space - the LIF volume
3) tar tv #This should start listing all the files on the tape. If it gets through all of them you can be "reasonably" sure the tape is OK.
Rgds,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!