Re: alarming experience with controlfile autobackup on
- From: Dragutin Jastrebic <orahawk@xxxxxxxxx>
- To: keydana@xxxxxx
- Date: Mon, 5 Nov 2012 22:53:35 +0100
Hello,
To clarify all this, I did 2 quick tests:
The testcase with a file drop
(autobackup is on, the tablespace test is composed of 3 files: test1,test2
and test3)
1) Backup database
2) Alter tablespace test drop datafile 'test2';(first backup of the
controlfile is created in fra/autobackup/) for exemple at 12:00 PM
2) Alter tablespace test drop datafile 'test3';(another backup of the
controlfile is created in fra/autobackup/) for exemple at 12:05 PM
3) delete obsolete (with redundancy 1 , the first backup of the
controlfile is deleted)
4) shutdown
6) startup nomount;
7) restore controlfile from autobackup;
7) restore database to time "to_date(.....12:03PM....)" (to the time before
the datafile test3 was deleted)
8) recover database to time "to_date(.....12:03PM....)"
9) alter database open resetlogs;
What is the result ? The database was restored and recovered to the point
in time when test3 existed, but this file is not restored since the new
controlfile does not see it. So yes, you can say that the database was
brought to state that never existed , to the point in time 12:03 PM but
without the datafile test3.
This is a normal and expected behaviour, all files were restored and
recovered to their point in time,except the files that are unkown to the
control file used. One more reason to use the rman catalog.
And this behaviour is not specific for autobackup controlfile on feature,
every time you are doing a restore/recover with the controlfile that does
not see some files, those files will not be restored
The testcase with a file add
1) Backup database
2) Alter tablespace test add datafile 'test2';(first backup of the
controlfile is created in fra/autobackup/) for exemple at 12:00 PM
2) Alter tablespace test add datafile 'test3';(another backup of the
controlfile is created in fra/autobackup/) for exemple at 12:05 PM
3) delete obsolete (with redundancy 1 , the first backup of the
controlfile is deleted)
4) shutdown
6) startup nomount;
7) restore controlfile from autobackup;
7) restore database to time "to_date(.....12:03PM....)" (to the time before
the datafile test3 was added)
8) recover database to time "to_date(.....12:03PM....)"
9) alter database open resetlogs;
The datafile test3 was displayed in v$datafile in 'recover' state after the
recover command and its checkpoint_time (12:05) was different from all
other datafiles (12:03) in v$datafile_header.
After <alter database open resetlogs>, it has disapeared from dictionnary
views,in spite of the fact that the controlfile saw it, because the
database was brought to the point in time before it was created.
So, again, this is the expected behaviour
HTH
Dragutin
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