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Archiver Processes (ARCn) (124)

原创 数据库开发技术 作者:tsinglee 时间:2007-11-01 09:54:21 0 删除 编辑

The archiver process (ARCn) copies redo log files to a designated storage device after
a log switch has occurred. ARCn processes are present only when the database is in
ARCHIVELOG mode, and automatic archiving is enabled.
An Oracle instance can have up to 10 ARCn processes (ARC0 to ARC9). The LGWR
process starts a new ARCn process whenever the current number of ARCn processes is
insufficient to handle the workload. The alert log keeps a record of when LGWR starts
a new ARCn process.
If you anticipate a heavy workload for archiving, such as during bulk loading of data,
you can specify multiple archiver processes with the initialization parameter
LOG_ARCHIVE_MAX_PROCESSES. The ALTER SYSTEM statement can change the value of
this parameter dynamically to increase or decrease the number of ARCn processes.
However, you do not need to change this parameter from its default value of 1,
because the system determines how many ARCn processes are needed, and LGWR
automatically starts up more ARCn processes when the database workload requires

日志切换时将重做日志文件拷贝到指定的存储设备 , 只有在归档模式并且自动归档时才可用
最多能有10个 , 通过LOG_ARCHIVE_MAX_PROCESSES可以指定多个归档进程 , 但这是没有必要的 ,
Oracle可决定需要多个少归档进程 , LGWR也可以启动该进程 .


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