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Oracle Tips by Burleson Consulting
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The System Monitor
background process (SMON)
The SMON background process performs all system monitoring functions
on the Oracle database. The SMON process performs a “warm start”
each time that Oracle is re-started, ensuring that any in-flight
transaction at the time of the last shutdown are recovered. For
example, if Oracle crashed hard with a power failure, the SMON
process is attached at startup time, and detects any uncompleted
work, using the rollback segments to recover the transactions. In
addition, SMON performs periodic cleanup of temporary segments that
are no longer needed, and also perform tablespace operations,
coalescing contiguous free extents into larger extents.
In UNIX, the SMON process will always be executing, and you can tell
when SMON is performing a coalesce operation because the CPU usage
for the process will increase.
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