当非system的datafile 无法写入时，控制db instance crash 还是 datafile offline的 参数

本文摘自：mos文章

Bug 7691270 - Crash the DB in case of write errors (rather than just offline files) (Doc ID 7691270.8)

Bug 7691270  Crash the DB in case of write errors (rather than just offline files)   This note gives a brief overview of bug 7691270.
 The content was last updated on: 15-JUL-2011
 Click here for details of each of the sections below.

Affects:

Product (Component)	Oracle Server  (Rdbms)
Range of versions believed to be affected	Versions BELOW 11.2.0.2
Versions confirmed as being affected	11.1.0.7 10.2.0.3
Platforms affected	Generic (all / most platforms affected)

 The fix for this bug introduces a notable change in behaviour thus:
   Notable change of behaviour introduced in 11.2.0.2

Fixed:

This issue is fixed in

11.2.0.2 (Server Patch Set)

Description

This fix introduces a notable change in behaviour in that 
from 11.2.0.2 onwards an I/O write error to a datafile will
now crash the instance.

Before this fix I/O errors to datafiles not in the system tablespace 
offline the respective datafiles when the database is in archivelog mode. 
This behavior is not always desirable. Some customers would prefer 
that the instance crash due to a datafile write error.

This fix introduces a new hidden parameter to control if the instance
should crash on a write error or not:
  _datafile_write_errors_crash_instance 



With this fix:
 If _datafile_write_errors_crash_instance = TRUE (default) then
  any write to a datafile which fails due to an IO error causes 
  an instance crash. 

 If _datafile_write_errors_crash_instance = FALSE then the behaviour
  reverts to the previous behaviour (before this fix) such that
  a write error to a datafile offlines the file (provided the DB is
  in archivelog mode and the file is not in SYSTEM tablespace in 
  which case the instance is aborted)
 

References

Bug:7691270  (This link will only work for PUBLISHED bugs)
Note:245840.1  Information on the sections in this article