Re: Oracle 10g, standby creation

"joel garry" <joel-garry_at_home.com> a écrit dans le message de news: bacdc7c4-a8c6-4342-8a92-6232394cd3d6_at_u16g2000pru.googlegroups.com... On Oct 26, 10:45 pm, Fabrice <t..._at_test.com> wrote:
> Hello
>
> I would like to create a physical standby with Oracle 10g.
> 2 servers with the same the same structure.
>
> I have read a lot of documentation but I'm always confused about some
> points.
>
> I would like to recplicate files from my production server to my standby
> server. So, U have created the same directory for :
>
> 1. pdump, adump..
> 2. and all the files : control files, datafile and online redologs.
>
> After cold backup :
>
> - Do I need to copy the backup of the production online redologs to my
> standby server. Do the standby could use it ?
> Or will they be create automatically by Oracle if one day the standby is
> activated ?
>
> - standby redo logs :
> It's very hard for me to know what to do with it.
> I have understand (i hope) that you need them if we use LGWR instead of
> ARC.
> But my confusion is where to create them : Some articles create standby
> redo
> logs only on the primary .. others on the standby. None on the both.
> And sorry I don't undertstand why.
>
> For me, SRL are used by oracle (lgwr/rfs) to write enties directly in it
> from primary to standby if we use LGWR mode. So You should create the SRL
> on the standby. But I'm not sure. Why some people do the creation on the
> primary and not on the standby ?
>
> If we create SRL on the standby, this one should have :
> - copy of the cold backup of the online redologs (from primary)
> - and n + 1 SRL.
> Willo the standby use the copy of the online redo ?
>
> thanks for your help.
> fabrice

You should pretty much never backup online redologs. The reasoning is, if you restore online logs over more recent logs, you will lose data. For cold backups, there is nothing in the redo, since the db was brought down correctly. If the db was brought down correctly. Look at the alter database backup controlfile to trace output, note the resetlog options. (There are obscure exceptions where you want redologs, but don't even think about it until you understand and have experience with everything else).

As far as srl's, see
http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/dbresource.htm#sthref487

"If you are configuring the maximum protection or maximum availability level of protection, you must add standby redo log files on all standby databases. Also, Oracle recommends you add standby redo log files on the primary database in preparation for a future switchover or failover. Standby redo log files are required on the primary database if you want the broker to automatically reinstate the old (failed) primary database after a fast-start failover."

You should understand that standby databases are merely databases in constant recovery. So, you should not be afraid of recovery, and especially be not afraid of hot backups through RMAN. Note that RMAN doesn't even let you backup redo logs, only archived logs.

jg

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Thanks for your answer.
I just want to use the cold backup to create my standby. I prefer do it 
manually and understand all the steps.
But, if  I don't copy the redologs in my standby from the primary during the 
standby creation I will have only standby redologs. If later, I realize a 
switchover (so my standby is the primary) what redologs Oracle are going to 
use ?
Not the standby redologs because they are use only for the standby role. Are 
the online redologs in the standby (primary now) going to be created from 
scratch by oracle If I realize a switchover ?

Thnaks fabrice.