DBWR is a background process that writes data blocks information from Database buffer cache to datafiles.
There are seven important situations when DBWR writes to data file:
- Every 3 seconds.
- Whenever a checkpoint occurs.
- When server process needs free space in database buffer cache to read new blocks.
- Whenever some blocks reaches a maximum value.
- Timeout occurs.
- RAC ping request is made.
- When any tablespace is taken offline, read only, drop or truncated & when to begin the backup.