Recover datafile in no archivelog mode

Question

Hi, i have always done media recovery using RMAN and this works nicely.
However im doing some testing on a database that does not use RMAN and is not in archivelog mode and im confused.(11.2 -  aix)
My testing is as follows;
With the database shutdown cleanly i have taken a copy of dbf file. I then open the database and delete the dbf file.
(to slightly digress how can i still view and update the table from this datafile when the dbf file is dropped?)
In scenario 1 i shutdown the database after dropping the file. I then put the dbf file back and try and startup the database.
I thought that as i have a complete consistent backup i would be able to open the database normally without recovery, but this produced an error saying the file needed media recovery  so i recovered the datafile and put online and the the db opened normally.
In scenario 2 i again took a clean backup and removed the dbf file. I then opened my database and switched redo logs 3 times ( i have 3 redo logs). After the 3rd switch the database crashed (which makes sense).
I have tried opening it normally again butagain it says the file needs media recovery. i then tried to recover the file but now i the following error:
ORA-00279: change 6667823 generated at 12/17/2013 11:35:20 needed for thread 1
ORA-00289: suggestion :
/test/oracle/TSTA/TSTA/archivelog/2013_12_17/o1_mf_1_78_%u_.arc
ORA-00280: change 6667823 for thread 1 is in sequence #78
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
Any help would be greatly appreciated

Answer 1

885842 wrote:
Hi, i have always done media recovery using RMAN and this works nicely.
However im doing some testing on a database that does not use RMAN and is not in archivelog mode and im confused.(11.2 -  aix)
My testing is as follows;
With the database shutdown cleanly i have taken a copy of dbf file. I then open the database and delete the dbf file.
(to slightly digress how can i still view and update the table from this datafile when the dbf file is dropped?)
In all *nix systems, the file is still there and open by any processes that had it open when you issued the 'rm' command.  It is not really deleted until all processes that have it open have terminated.
In scenario 1 i shutdown the database after dropping the file. I then put the dbf file back and try and startup the database.
I thought that as i have a complete consistent backup i would be able to open the database normally without recovery, but this produced an error saying the file needed media recovery  so i recovered the datafile and put online and the the db opened normally.
The backup may have been consistent, but if you restored only that one file, it was several SCN's behind the other files that continued to be updated after you took the consistent backup.  "Consistent" means not only consistent interally to the individual file, but consistent with all other data files, plus the control files, plus the redologs.
In scenario 2 i again took a clean backup and removed the dbf file. I then opened my database and switched redo logs 3 times ( i have 3 redo logs). After the 3rd switch the database crashed (which makes sense).
I have tried opening it normally again butagain it says the file needs media recovery. i then tried to recover the file but now i the following error:
ORA-00279: change 6667823 generated at 12/17/2013 11:35:20 needed for thread 1
ORA-00289: suggestion :
/test/oracle/TSTA/TSTA/archivelog/2013_12_17/o1_mf_1_78_%u_.arc
ORA-00280: change 6667823 for thread 1 is in sequence #78
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
Any help would be greatly appreciated
You said you are not in archivelog mode.  So where did this reference to an archivelog come from?