Hi Joseph,
You are right, because I configured ADSM to use DASD (file) as output device 
this was the case. We let ADSM make disk datasets which we migrate to tape 
using our DASD management system (SAMS:DISK) later on. I simulated what would 
happen if a output dataset was reused the next day (after being migrated to 
level 2 which causes a idle space release).
So you are right about the cause which resulted in the "read only" status, but 
that is not my problem. I'm surprised about the fact that ADSM stops the backup 
processing on the client! Why isn't a new volume mounted?
Kind regards,
Eric van Loon