I have configured NMO oracle online database backup by legacy method but backup is getting hanged. Saveset is showing active but not generating any channels. File System backup is happening and also RMAN backup is happening from client side. I have checked everything but unable to find the issue.Kindly help.
Well, hang can happen for many reasons (and majority of reason usually lives on Oracle side). You didn't say which system Oracle is running on. If UNIX/Linux, can you make strace on oracle channel OS PID process and see what you get (if FUTEX_WAIT, then it is easy).
Actually this discussion related to "Linux-x86_64 Error: 28: No space left on device while taking NMO oracle database backup" created by me. "oracle channel OS PID process" you mean to say through debugging option (NSR_DEBUG_FILE).