关于参数log_file_name_convert

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One response to “关于参数log_file_name_convert”

1. 

   admin

   August 17, 2010

   Usage of db/log_file_name_convert parameters
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   ORACLE
   ——————————
   
   —————-
   FREQUENTLY ASKED QUESTIONS
   ————————–
   17-MON-2004

   CONTENTS
   ——–
   1. Can the parameter db_file_name_convert be used to rename the files as
   part of restore of the target backups?

   2. Can the parameter log_file_name_convert be used to rename the the logfiles
   as part of a manual restore of target to a different location?

   3. Does parameter log_file_name_convert enable to add logfile to standby
   when adding ones into primary?

   QUESTIONS & ANSWERS
   ——————-
   1. Can the parameter db_file_name_convert be used to rename the files as
   part of restore of the target backups?

   Answer
   ——
   It is a common mis-conception regarding the usage of db_file_name_convert.

   The parameter db_file_name_convert is used to rename the datafiles being
   restored from the target backups into an “auxiliary” instance.
   But it cannot be used to rename the files in the target instance itself.

   This parameter is usually used in the following 3 cases:
   ++ Creation of a standby from the target using:
   “duplicate target database for standby …;”
   ++ Creation of a duplicate database from the target using:
   “duplicate target database to ‘xxx’…;”
   ++ RMAN Tablespace point in time recovery using:
   “recover tablespace ‘xxx’ until ‘xxxx’..;”

   In all the above cases the datafiles are restored to the location mentioned in
   the parameter db_file_name_convert or as specified by “set newname for …..”
   command. Once the files are restored then the “auxiliary”(/duplicate/clone/..)
   controlfile is created and the files are renamed to the location specified by
   the parameter. All this happens as part of memory scripts.

   This is not the case with a manual restore of the target to a new location.
   In that case the the files are restored to location contained in the controlfile
   and the parameter db_file_name_convert is not used at all.

   In case of creating standby database manually db_file_name_convert and
   log_file_name_convert parameter can be used if db/log file location is
   different in primary and standby.

   Please note that setting db_file_name_convert would not change file location in
   controlfile but memory only for the instance. The standby control file will
   keep original location information until you change them using
   ‘alter database rename file .. ‘ command. If restarting standby after
   removing (commenting out) db_file_name_convert, the standby will be started with
   same location for db/log files and may errors output when opening read only
   or applying archive logs.

   In short, the parameter cannot be used to rename and restore files into the
   target database itself.

   2. Can the parameter log_file_name_convert be used to rename the the logfiles
   as part of a manual restore of target to a different location?

   Answer
   ——
   The answer again is NO.
   The explanation of the first question holds good for the online redologs as well.
   Though the logfiles are not restored but are created as part of an “open resetlogs”.
   In that case again the controlfile would not be renamed using the parameter and
   would still be pointing to the original location.

   3. Does parameter log_file_name_convert enable to add logfile to standby when
   adding ones into primary?

   Answer
   ——
   The answer again is No.
   Redo, standby redo and temp files are managed separately in primary and standby
   environment. Adding redo into primary would not add same to standby automatically
   even with log_file_name_convert.

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