可以通过隐藏参数_datafile_write_errors_crash_instance控制DBWR进程写出到数据文件遇到I/O问题时的表现:
在版本11.2.0.2中:
1. 默认情况下,若是RAC或未启用归档的实例或出现问题的是SYSTEM表空间的数据文件会导致实例终止;其他情况下,会造成相关数据文件被OFFLINE。
2.若该参数设置为TRUE,则在DBWR写文件出现问题时总是终止本实例
3. 若设置为FALSE,仅在未启用归档或SYSTEM表空间的数据文件的情况下会终止实例;
” The new behavior is defined by _datafile_write_errors_crash_instance
parameter. Parameter has no default value and 3 different behaviors depending
if it is set and to which value. For default behavior (param not set) the
instance is crashed if RAC or archivelog mode is disabled or this is a system
tablespace. Otherwise the file is offlined. If param is set to TRUE, it is
crashed in all cases. If set to FALSE, it is crashed only if archivelog mode
is disabled or this is a system tablespace.”
参数并不能完全保证实例不受IO错误影响而意外终止,且设置该参数可能导致数据文件被OFFLINE。 具体设置方法,该参数可以在线设置:
SQL> alter system set “_datafile_write_errors_crash_instance”=false;
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