Re: benefits of multiple switch logfile calls?

Brian Peasland <dba_at_remove_spam.peasland.com> wrote in message news:<3FCE5C98.1EDE2220_at_remove_spam.peasland.com>...
> > 3 log groups? Make sure all switched?
>
> Sure...but why? After all this is said and done, one still has one
> active log group. No different than if you just issued one switch.
>
> Cheers,
> Brian
>
>
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>
> Brian Peasland
> dba_at_remove_spam.peasland.com
>
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> "I can give it to you cheap, quick, and good. Now pick two out of
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I'm not sure of where you are mentally on all this. The switch log files / archive log files, to my knowledge is intending to get any current redo out of the online redo logs and into the archive redo logs.

I'm not completely clear on switching vs archiving. I would think that just archiving would be enough.

What I am certain of is that while your tblspaces are in "begin backup" and you are gziping or copy data files, transactions and / or checkpoints are occuring in your system. After you do the "end backup" it is wise to get all redo out to the archive directory.

Then when you restore and do the recovery command (our recovery command is "recover database using backup controlfile until cancel") the recovery will only need archived redo logs.

In fact what we do is not restore the online redo logs at all, we let the database rebuild them during the recovery. I will explain why.

We do backups similar to you, but use netbackup to copy the files to tape. This copy can take from 10 minutes to 6 hours depending on the size of the db. If we let the system backup the redo logs, who knows where in the time frame they will get backed up. If we back them up after the "end backup" they will contain advanced data. So we like to control the whole situation by doing the "end backup" followed by:

alter system checkpoint;
alter system switch logfile;
host sleep 10
alter database backup controlfile to '$gOUT_DIR/cntrlfile'; alter database backup controlfile to trace;

Note I now believe these last steps are out of order. I think we should get the controlfile backup first, and then get the log switch. Note we do restore the backup of the control file before the recovery because again who knows where in the backup process the controlfile was backed up. Received on Thu Dec 04 2003 - 09:55:46 CST