Oracle Database Background Processes
Database writer (DBWn)
The database writer writes modified blocks from the database buffer cacheto the files on a disk. Oracle Database allows a maximum of 36 databasewriter processes.
数据库写进程
数据库写进程将数据库高速缓冲区中被修改的模块写入磁盘上的文件中。Oracle数据库允许最大有36个写进程。
Log writer (LGWR)
The log writer process writes redo log entries to disk. Redo log entries aregenerated in the redo log buffer of the System Global Area (SGA) and thelog writer process writes the redo log entries sequentially into an onlineredo log file.
日志进程
日志写进程将重做日志项写入磁盘中，重做日志项实在系统全局域的重做日志缓冲区中生成的，日志写进程将重做日志项顺序写入在线重做日志文件中。
Checkpoint (CKPT)
At specific times, all modified database buffers in the SGA are written to the data files by a database writer process (DBWn). This event is called a checkpoint. The checkpoint process signals DBWn, updates the data filesand control files of the database, andrecords the time of this update.
检查点
在特定时间，系统全局域中所有被修改的数据库缓冲区都会给数据库写进程 写入数据文件中。这个时间称为检查点。检查点进程给数据库写进程发信号，更新数据文件、数据库控制文件并且记录这次的更新记录。
System monitor (SMON)
The system monitor performs instance recovery when a failed instance isrestarted.
系统监视
当一个实例重启时，系统监视进程就会执行实例恢复任务。
Process monitor (PMON)
The process monitor performs a recovery when a user process fails. It cleans up the cache and frees resources that thefailed process was using.
进程监视
当一个用户进程出现故障时，进程监视进程就会执行恢复任务。当出现故障的进程正在被使用时，进程监视进程就会清除缓冲数据并且释放资源。
Archiver (ARCn)
Archiver processes copy the online redo log files to archival storage whenthe log files are full or a log switch occurs. The database must be in archive log mode to run archive processes.
归档器
当日志文件报满或者日志切换时，归档进程就会将在线重做日志文件复制到归档区中，要运行归档进程，数据库必须处于归档模式。
Manageability monitor
This process performs various management-related background tasks, forexample:
■ Issuing alerts whenever a given metric violates its threshold value
■ Taking snapshots by spawning additional processes
■ Capturing statistical values for SQL objects that have been recently modified(MMON)
管理监视器
这个进程执行多种有关后台任务管理项目。比如：
■当超过自身阈值时分发警告
■通过生成额外的进程来撷取快照
■获取被修改的SQL对象统计数据
Job Queue Processes (CJQ0and Jnnn)
Job queue processes runuser jobs, often in batch mode. A job is auser-defined task scheduled to run one or more times.
作业序列进程
作业序列进程执行用户作业，通常处于批处理模式。一个作业就是一个用户定义的预定任务，执行一次货多次。