Errores y bugs relacionados con el DBWn (Database Writer Process)

The primary responsibility of DBWn is to write data blocks to disk. DBWn also handles checkpoints, file open synchronization, and logging of Block Written records.

In many cases the blocks that DBWn writes are scattered throughout the disk. Thus, the writes tend to be slower than the sequential writes performed by LGWR. DBWn performs multiblock writes when possible to improve efficiency. The number of blocks written in a multiblock write varies by operating system.

The DB_WRITER_PROCESSES initialization parameter specifies the number of DBWn processes (DBW0-DBW9 and DBWa-DBWz). The database selects an appropriate default setting for this parameter or adjusts a user-specified setting based on the number of CPUs and processor groups.

Issues Specific to DBWn

Note 243248.1 - Database Startup fails with ORA-443 Background Process "DBW0" did not Start

Note 1065267.6 - ORA-445 Background Process DBW0 Did Not Start After 120 Seconds

Note 1461704.1 - ORA-00600 [kcbbxsv_2] Errors And DBW0: Terminating Instance Due To Error 471 (

Note 6005113.8 - Bug 6005113 - OERI[kclrwrite_7] in DBWn process followed by instance crash in RAC