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RE: FW: backing up rman catalog for disaster recovery

From: Marquez, Chris <cmarquez_at_collegeboard.org>
Date: Thu, 26 May 2005 12:26:12 -0400
Message-ID: <B30C2483766F9342B6AEF108833CC84E0450BBE0@ecogenemld50.Org.Collegeboard.local> 





Charlotte,


>>I must confess to being equally paranoid but in a slightly different way

>>I have a script that checks the RMAN logs and also looks in the backup directory to see what's there.




Nice...yet another paranoid, doubting, tormented DBA.
I thought it was just me...I'm in good company.
 ;o)



Chris Marquez


Oracle DBA





-----Original Message-----


From: oracle-l-bounce_at_freelists.org on behalf of Charlotte Hammond
Sent: Thu 5/26/2005 12:06 PM


To: ORACLE-L


Subject: RE: FW: backing up rman catalog for disaster recovery
 


Hi Chris,


"Marquez, Chris" <cmarquez_at_collegeboard.org> wrote:



Charlotte,



I found these (see below) in my personal RMAN notes.
While my immediate comments (below) about "CONFIGURE CONTROLFILE AUTOBACKUP" might be misguided (based on what I believe you are saying) the bug issue (below that) was very real for me at the time we first when to 9i.




I've not seen any problems like this on 9.2.0.5 so hopefully it *is* fixed :-)  However since, you're restoring by filename rather than letting RMAN automatically find the file you'd probably be circumventing this problem anyway (I think).

 




Here is one more thing (is a personal problem not a technical one.)
I hate 9i "CONFIGURE" parameters...if I use them I *ALWAYS* re-set them 1st thing with *ALL* of my RMAN (shell) scripts.
"But they are *persistent"...yes....but I'm a well trained paranoid DBA...I assume that between backsup the Evil Empire will log into my database and change my *persistent* "CONFIGURE" parameters and thus my backup will be different, missing stuff.  Again I said it was a personal problem not a technical one...but nobody ever changes anything in a database, right? :0|




I completely understand your caution - been stung by this too.  However if you are always resetting CONFIGURE parameters at the start of your scripts you can simply CONFIGURE AUTOBACKUP ON too (to make sure it is on...)



I must confess to being equally paranoid but in a slightly different way - I have a script that checks the RMAN logs and also looks in the backup directory to see what's there.  And one of the things checked? The presence/absence of a recent controlfile autobackup!  




Having said that you have given me new hope and I again will try the "CONFIGURE CONTROLFILE AUTOBACKUP"...along *with* my tried-and-true "copy controlfile" syntax...It never hurts to have more backup controlfiles. ;o)




Absolutely!






Thanks,



Chris Marquez


Oracle DBA




>>  - "CONFIGURE CONTROLFILE AUTOBACKUP"


>> I do not use this, but will look at my notes to see if I tested it.

>> This statement concerns me;

>>   "a manually backed-up controlfile cannot be automatically restored."

>> This implies that a "CONTROLFILE AUTOBACKUP" can be automatically restored...but I disagree, about the usefulness of that..or the reality of that.

>> Again, using the RMAN rule (really all backup software rule), if I don't "Backup Meta Data", how can I restore anything!?

>> And if I do have a current controlfile ("Backup Meta Data") that can automatically restore my "CONTROLFILE AUTOBACKUP", that means the current controlfile is more current than the controlfile I will restore!...why do that?

>> The only way I see that CONTROLFILE AUTOBACKUPs might be useful is if it is a separate and identifiable RMAN file (set).  Meaning I *might* be able to pick it out from a list of other RMAN backup files (sets.  Then it can use it by RMAN to "replicate" or OS to "cp" it back as my database controlfile(s)).

>> Even still this controlfile backup would not be aware of subsequent archive log backups.








CONTROLFILE AUTOBACKUP





CONFIGURE CONTROLFILE AUTOBACKUP  ON | OFF | CLEAR;


Bug:2458246 RMAN WRONGLY THINKS BACKUPS WITH SPFILE ARE OBSOLETE 




If you have RMAN backups that include the SPFILE, and you do either REPORT OBSOLETE or DELETE OBSOLETE with RMAN,
then RMAN might incorrectly report or delete  certain backups as obsolete, even if they weren't.  




    
  
  1.   Don't use the SPFILE ..instead use the init.ora parameter file  
  
  2.   Include in your scripts...
         RMAN> backup current controlfile;     
This will add the controlfile in a different piece handle that the autobackup command.  
  
  3.   Don't use the autobackup command. (set OFF) 

    
Fixed in: 9.2.0.2 and 10i


    





# Configure RMAN to back up the control file after each backup.
CONFIGURE CONTROLFILE AUTOBACKUP ON;


# Configure RMAN to write controlfile autobackups to the /backup directory.
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/backup/ora_cf%F';



-----Original Message-----


From: oracle-l-bounce_at_freelists.org on behalf of Marquez, Chris
Sent: Thu 5/26/2005 9:43 AM


To: charlottejanehammond_at_yahoo.com; ORACLE-L
Subject: RE: FW: backing up rman catalog for disaster recovery



Charlotte,


Good to know and I believe I have heard something of this.
Could you provide the snip of RMAN syntax that would generate the "controlfile autobackup" or is it one of the 9i "CONFIGURE" parameters?
Is the "controlfile autobackup" allways generated as the *last* backup object int the RMAN session?



Also, what does one of these files looks like.  I often suspect that I have a (auto created) backup controlfile, but I all of my backsets use the same formant...not able to differentiate then much other than size?




>>RMAN> restore controfilefile from '<name of autobackup file>';




So I can remover *all* of my controlfiles, startup nomount with the correct init.ora file and run this command and get my controlfile back...pushed into the right place(s) as identified in my init.ora...similar/same idea as the RMAN "replicate controlfile" command syntax?...Or I could simple "$>cp..." it to my correct controlfile location and names?



Thanks,



Chris Marquez


Oracle DBA



-----Original Message-----


From: oracle-l-bounce_at_freelists.org on behalf of Charlotte Hammond
Sent: Thu 5/26/2005 6:02 AM


To: ORACLE-L


Subject: RE: FW: backing up rman catalog for disaster recovery



I agree that an RMAN scripted backup controlfile is not useful, but configuring RMAN controlfile autobackup does help:



    
  
  1.   You then don't have to include a copy command (internal or external) for you controlfile as RMAN does it for you automatically.

  
  2.   The filename of the autobackup contains both the date and the database ID in a human readable format.






To get your controlfile back (without needing a catalog) you just need to do



RMAN> restore controfilefile from '<name of autobackup file>';





---



>>I just cheated and backed up the control file separately


"Cheat" nothing this is just smart...or reality :o|



>> run {allocate channel c4 type disk; copy current controlfile to...




>> in my shell script *every* time and AT THE END OF EACH BACKUP




>> NOT an RMAN *backup* of my controlfile (totally useless),




>> but rather a *COPY* of my controlfile.




>> Meaning it can be used without RMAN;


As I said in an earlier post, RMAN backup controlfile (IMHO) is rather useless.

It is the classic "chicken and egg".

You have a controlfile in the RMAN backup, but you need a current controlfile to get to the backup! (in the absence of a recover catalog). If I have a current controlfile then why do I need the one *in* the backup?

Oracle should update the RMAN documentation it indicate thsi mental puzzle.

Seems everyone learns this the hard way during testing...or the really hard way during a disaster.

Anyone want to guess...

What would be of some use when all current controlfiles and datafiles are lost and you have >1 good RMAN backups? (A worst case senario).



Chris Marquez

Oracle DBA



-----Original Message-----

From: oracle-l-bounce_at_freelists.org on behalf of Dennis Williams

Sent: Wed 5/25/2005 6:15 PM

To: rgramolini_at_tax.state.vt.us

Cc: oracle-l

Subject: Re: FW: backing up rman catalog for disaster recovery



Actually, RMAN always writes to the control file before it updates the

catalog. So even if you do an RMAN backup using a catalog, you can

still recover the database using only the controlfile. Now, in

Oracle8i I had problems recovering the control file from the RMAN

backup, so I just cheated and backed up the control file separately

after the RMAN backup completed, and made sure the control file backup

was on the same tape as the RMAN backup. I have performed many

recoveries using this method.

Dennis Williams

On 5/25/05, Ruth Gramolini <rgramolini_at_tax.state.vt.us> wrote:

>=20

>=20

> One very easy way is to do an rman backup with the nocatalog option. Thi=

s

> will use controlfile info for restores and recoveries. You can use all t=

he

> options of rman, just no catalog. That is what we do.

>=20

> Just my $0.02,

> Ruth

>=20

> -----Original Message-----

> From: Paula_Stankus_at_doh.state.fl.us

> [mailto:Paula_Stankus_at_doh.state.fl.us]

> Sent: Wednesday, May 25, 2005 4:49 AM

> To: Paula_Stankus_at_doh.state.fl.us; rgramolini_at_tax.state.vt.us;

> all_about_oracle_at_hotpop.com; oracle-l_at_freelists.org

> Subject: RE: backing up rman catalog for disaster recovery

>=20

>=20

> I am setting up a disaster recovery site and I was thinking about the

> best way to do this.

>=20

> My theory is that I would like to not just use another recovery catalog

> on the DR site to backup my primary catalog but to somehow keep these

> catalogs constantly in-synch so when I do need to do complete recovery

> and only have the secondary rman catalog available - I wouldn't have to

> recover the catalog as all of the previous backups would be found there.

>=20

> So....should I do this using Oracle Data Guard on my disaster recovery

> site catalog or backup rman then restore as my first procedure? Any

> advice?

>=20

> --

> http://www.freelists.org/webpage/oracle-l

>

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Received on Thu May 26 2005 - 12:34:47 CDT












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