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Restoring live database datafile from standby
Hi all,
o/s: rhel 4
db : 10.2.0.3 RAC/Dataguard config using ASM
I have a situation where i need to move datafiles on my primary database from one ASM diskgroup to another due to a faulty LUN. However some of moves are not working as the copy of some datafiles is taking too long even the all the datafiles are roughly the same size (most have been successfully moved). As we also have a dataguard config, I was wondering if we could take a backup of the particualar datafile on the standby and restore it to the new diskgroup on LIVE? Is this possibe and if so i would appreciate the steps we need to take using RMAN?
Any advice would be appreciated,
Thanks,
Chucks
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Hi
You need to find out if your disks are slow while copying .
If your standby database is on the same LAN as the primary then copying the datafile from standby to primary will also work.
Try
Code:
On Primary
RMAN>sql 'alter database datafile 5 offline'
on Standby
RMAN>copy datafile '/odb/datafile/my.dbf' to '/tmp/my-copy.dbf'
copy the datafile my-copy.dbf to primary server at /tmp/my-copy.dbf
On Primary
RMAN>catalog datafilecopy '/tmp/my-copy.dbf'
RMAN>switch datafile 5 to COPY
RMAN>recover datafile 5;
RMAN> sql 'alter database datafile 5 online';
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Thanks Hrishy!
On my standby the files in located in a directory which is different from the live db, hence do I need to run a set newname before the switch?
Thanks in advance,
Chucks
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Hi
Nope since you are copying the file from standby to primary setnewname is not required.
The catalog command will tell rman where to look for the file on the primary.
regards
Hrishy
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Thanks Hrishy,
I just realised, the steps you have given me will still mean that the copy of the datafile will reside in the same diskgroup on the live db. Because the LUN is suspect, will be able to move the datafile again to another diskgroup. In your steps can we restore to copy to another diskgroup straight away?
Thanks in advance
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Hi
I gave you a general outline you can copy the datafile from the standby to anywhere on the primary server.
For example you are copying the datafile to /tmp/my-copy.dbf using OS commands.
You can for example do this after you have added the datafile 5 to a filesystem from standby .
Code:
RMAN> REPORT SCHEMA;
RMAN> BACKUP AS COPY DATAFILE 5 FORMAT '+TEST';
RMAN> switch datafile 5 to COPY;
RMAN> REPORT SCHEMA;
At the end of abouve steps you have moved the datafile to ASM diskgroup
If you want to copy the datafile from standby directly to ASM diskgroup on the primary server then you need to use dbms_file_transfer and copy the datafile over to that diskgroup
regards
Hrishy
Last edited by hrishy; 03-04-2008 at 06:52 AM.
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Hi Hrishy,
Thanks for that, just so i am clear the steps then would be:
Code:
On Primary
RMAN>sql 'alter database datafile 5 offline'
on Standby
RMAN>copy datafile '/odb/datafile/my.dbf' to '/tmp/my-copy.dbf'
copy the datafile my-copy.dbf to primary server at /tmp/my-copy.dbf
On Primary
RMAN>catalog datafilecopy '/tmp/my-copy.dbf'
RMAN> BACKUP AS COPY DATAFILE 5 FORMAT '+TEST'; <- new ASM diskgroup for datafile
RMAN> switch datafile 5 to COPY;
RMAN>recover datafile 5;
RMAN> sql 'alter database datafile 5 online';
Thank you for all your help!
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Hi Chucks
I havent validated these but my bet is that the steps should be something like this
Code:
On Primary
RMAN>sql 'alter database datafile 5 offline'
on Standby
RMAN>copy datafile '/odb/datafile/my.dbf' to '/tmp/my-copy.dbf'
copy the datafile my-copy.dbf to primary server at /tmp/my-copy.dbf
RMAN>catalog datafilecopy '/tmp/my-copy.dbf'
RMAN>switch datafile 5 to COPY;
RMAN>report schema;
above step would switch the datafile to the copy that is present in the filesystem.
RMAN> BACKUP AS COPY DATAFILE 5 FORMAT '+TEST'; -->copy to the ASM diskgroup
RMAN>report schema;
RMAN>switch datafile 5 to COPY; -->point to the copy in the ASM filesystem
RMAN>recover datafile 5;
RMAN> sql 'alter database datafile 5 online';
RMAN>report schema -->Verify that file 5 is in the ASM diskgroup
check it out and let me know how it goes
The report schema statements are there just to make you feel comfortable that you verify that each step you are on the right track
regards
Hrishy
Last edited by hrishy; 03-04-2008 at 10:24 AM.
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Hi Hrishy,
Thank you very much for that. That has worked fine!
Thanks again,
Chucks
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