Hello,
Drive Firmware autolevel feature in Tape lib such as ADIC i2K  helps keep 
all drives within the Tape Lib at same Firmware level, Firmware mismatch 
can occur if drives are changes etc, all lib may not support this feature, 
check with the vendor.
As far as CDI, i have had conflicting information, in my environment, we 
had definite benefit by keeping "CDI OFF", so i would suggest turning it 
off and see if the problem goes away, if not leave it the way it is, you 
can also read up on what you gain or lose by this feature in Networker 
Guides and elsewhere.
HTH

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