DBWR

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DBWR (DataBase WRiter) is an Oracle background process created when you start a database instance. The DBWR writes modified data (dirty buffers) from the SGA into the Oracle database files. When the SGA data buffer cache fills the DBWR process selects buffers using an LRU algorithm and writes them to disk. There can be multiple database writer processes named DBWn.

SQL> show parameters db_writer
NAME				     TYPE	 VALUE
------------------------------------ ----------- -----
db_writer_processes		     integer	 1
SQL> SELECT spid, pname, username, program, tracefile FROM v$process WHERE pname LIKE 'DBW%';
SPID PNAME USERNAME PROGRAM
---- ----- -------- -----------------------------------
TRACEFILE
---------------------------------------------------------------------
3035 DBW0  oracle  oracle@localhost.localdomain (DBW0)
/home/oracle/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_dbw0_3035.trc
SQL> ! ps -f 3035
UID        PID  PPID  C STIME TTY      STAT   TIME CMD
oracle    3035     1  0 11:16 ?        Ss     0:00 ora_dbw0_orcl
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