Hi Sebastian,
"ERROR => e=28 semget(20110,1,2016) (28: No space left on device) [semux.c 508]
Looks like shared memory segments have exhausted. Following options can be used
1) Stop application and database . Perform cleanipc to clear shared memory segments
2) You may reduce the number of work processes on shadow instance to reduce the memory requirement for the instance to start.
3) For shadown instance profile, execute sappfpar check pf=<path of shadown instance profile> to determine the proposed value of shared memory segment size.
4) If you can manage to keep primary instance down, please do so and then start shadow instance. It should help.
Hope this helps.
Regards,
Deepak Kori