What will happen if oracle unable to write Alertlog, Core Dump Or Tracefiles

What will happen if oracle unable to write Alertlog, Core Dump Or Tracefiles  In this I will show what can happen if Oracle is unable to write to the  trace/alert. log to bdump or cdump & udump directories. It can  happen if you loss your background_dump_ dest or user_dump_dest or  core_dump_dest ormay the the partition containing bdump or udump folder  is full.