System Monitor (SMON): SMON performs automatic instance recovery. Rolling forward changes made in the redo logs to datafiles. Rolling forward is called redo applying. Rolling backward all the uncommitted transactions is called undo.
SMON performs the roll forward process by applying changes recorded in the online
redo log files from the last checkpoint. Roll back can occur while the database is open.
Either SMON or a server process can perform the rollback operation
Instance recovery restores a database to its transaction-consistent state just prior to instance
failure. The Oracle server automatically performs instance recovery using SMON.
Did you have a look at the Oracle documentation? Search for "SMON" in the below link.
Hi There ,
The system monitor process (SMON) is in charge of a variety of system-level cleanup duties. The duties assigned to SMON include:
SMON checks regularly to see whether it is needed. Other processes can call SMON if they detect a need for it.
As you know in case of db instance SMON will recover the instance when the instance failure occurs and clean up the temporary segments. Wheather SMON will do the same task in case of ASM instance.Kindly explain me the flow what happens for SMON,PMON processes in case of ASM Instance. In other word i want to know what background processes will do in case of ASM instance which are common to DB instance as ASM instance does not mount Database as well as SGA contains only Shared pool,large pool, ASM memory cache and free space.
The answer to your question, specific to ASM, is very little.
All the stuff that SMON does in a DB instance, simply doesn't exist/doesn't happen in ASM.
I tried doing 'strace' on SMON process, to confirm, and my observation was that it just doesn't really do much of anything.
This is consistent with the documented SMON activities, noe of which happen in ASM.
Hope that helps,
Ok as i found the answer for the same logically. SMON will do instance recovery and clean up temporary segments in ASM instance as well. Suppose process of ASM instance is killed manually due to which ASM instance is crashed after few minutes ASM instance in again restarted and disk are mounted. Here SMON will help to mount the diskgroup.
In a similar way can you please explain me functioning of PMON,DBWr.
Any idea about the same