Importance of monitoring

What could happen if you don’t monitor what’s happening?

CRASH.

Oracle 11.2.0.2+  new feature: if writes to a datafile fail, crash the database by default.

Go back to old ways:  by setting underscore parameter  _datafile_write_errors_crash_instance= false



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)
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