Instance crash – Parâmetro _datafile_write_errors_crash_instance

Recentemente administrando um banco 11.2.0.4, tive um estouro do disco onde estava localizado apenas o arquivo de dados da TEMP e posteriormente um crash da instância.

Verificado o motivo da queda, pude constatar que a partir da versão 11.2.0.2 a Oracle implementou o parâmetro _datafile_write_erros_crash_instance que por padrão vem definido como TRUE.

Desta forma, sempre que ocorrer qualquer erro de IO durante a escrita em um datafile ocorrerá uma queda da instância.

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)

Fonte: Doc ID 7691270.8
https://shrikantrao.wordpress.com/2012/07/09/io-write-error-effect-in-11-2-0-2/
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Jhonata Lamim

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