We recently started using an ATL with our MVS v2 server and have encountered a 
problem with the way the server deals with invalid labels.  We have submitted a 
request to ibm to enhance adsm to try another tape volume if it runs into a 
problem with a tape volume label.  We have two instances in which the internal 
label did not agree with the external label.  Instead of marking the volume 
unavailable (as I believe it does with r/w errors), ADSM just kept on trying to 
use the volume.  This brought server operations to a grinding halt.