RMAN - recovery

Asked Tom the below question. I don't understand his response (I just don't get it - how?!). I don't wanna pest him anymore. Can someone enlighten this dim wit (me)?

Thanks.

Excerpt :
"Just to replay the case - A single machine hosted the target and the catalog. The catalog was last backed up at 10pm last night. The target was backed up at 8am this morning (and at 8am yesterday, using the catalog). Target archivelogs were backed up every hour (using RMAN). The machine blew this afternoon at 4pm. I've lost EVERYTHING (including all controlfiles) concerning the target and the catalog. Unfortunately, I was then only able to restore the catalog as of a point in time - 10pm last night. Now, using this catalog - I can only restore an OLD target controlfile. No matter what, I would only be able to restore/recover the target database as of 10pm (or earlier) yesterday. Correct?" Note : Controlfile auto backup feature was NOT turned on for target


His response :
"you would get everything -- everything would be recoverable. The backed up data exists, it is out there. rman knows what it would have called it.

See chapter 10 of the 9ir2 rman guide -- various scenario's are played out there. In particular:

Performing Recovery with a Backup Control File and No Recovery Catalog"

-------------------

I've read the User guide. I've re-read the chapter 10 over and over again. I simply don't get it!! How would I be able to perform a complete recovery (excluding online logs ofcourse) with an outdated catalog and/or an old target controlfile?

Here's the thread if you're interested

http://asktom.oracle.com/pls/ask/f?p...:7145177199678

The bottom few posts on Jun 08 are by me.

PS : I won't be online Jun11 thru 14th. If you don't receive a reply to your response, you know why.

I don't get it either. It's a bit messy :-))

OK: if the control file is old, you restore and roll forward to the last archive you have on disk. Even if the control file has no entries of this "new archives" created after the backups, it will allow you to roll past this point. "Recover using backup controlfile".

If you have all the archivelogs on tape, you can restore them to disk, "catalog" them and you will be able to recover.

Hi

Tom Kyte is right.

The reason being RMAN always includes the control file in a backup operation that includes file 1 (system data file),regardless of the autobackup setting.

so u will be able to recover completely in your case.

for extracting the controlfile from the backupset when not using a catalog you need to do this

DECLARE
l_type VARCHAR2(256);
l_done BOOLEAN;
BEGIN
l_type := dbms_backup_restore.deviceallocate(type=>NULL,ident=>'d1');
dbms_backup_restore.restoresetdatafile;
dbms_backup_restore.restorecontrolfileto(cfname=>'/home/ora/new_control.ora');
dbms_backup_restore.restorebackuppiece(handle=>'/home/ora/control5.rman',
done=>l_done, params=>NULL);
dbms_backup_restore.devicedeallocate;
END;

regards
Hrishy

Or like this:

DECLARE
v_dev varchar2(50); -- device type allocated for restore
v_done boolean; -- has the controlfile been fully extracted yet
type t_fileTable is table of varchar2(255)
index by binary_integer;
v_fileTable t_fileTable; -- Stores the backuppiece names
v_maxPieces number:=1; -- Number of backuppieces in backupset
BEGIN
-- Initialise the filetable & number of backup pieces in the backupset
-- This section of code MUST be edited to reflect the available
-- backupset before the procedure is compiled and run.
-- In this example, the backupset consists of 4 pieces:
v_fileTable(1):='CCE_arfoc0fh_1_1';
v_fileTable(2):='CCE_asfoc125_1_1';
v_fileTable(3):='CCE_asfoch76_1_1';
v_fileTable(4):='CCE_asfockkj_1_1';
v_maxPieces:=4;
-- Allocate a device. In this example, I have specified 'sbt_tape' as I am
-- reading backuppieces from the media manager. If the backuppiece is on disk,
-- specify type=>null
v_dev:=sys.dbms_backup_restore.deviceAllocate(type=>'sbt_tape',ident=>'t1');
-- Begin the restore conversation
sys.dbms_backup_restore.restoreSetDatafile;
-- Specify where the controlfile is to be recreated
sys.dbms_backup_restore.restoreControlfileTo(cfname=>'/u02/oralog1/CCE/new_control.ora');
-- Restore the controlfile
FOR i IN 1..v_maxPieces LOOP
sys.dbms_backup_restore.restoreBackupPiece(done=>v_done,handle=>v_fileTable(i),params=>null);
IF v_done THEN
GOTO all_done;
END IF;
END LOOP;
<>
-- Deallocate the device
sys.dbms_backup_restore.deviceDeallocate;
END;
/

Quote:

---

Originally posted by julian

Code:

---

....
FOR i IN 1..v_maxPieces LOOP
  ....
  IF v_done THEN
    GOTO all_done;
  END IF;
END LOOP;
<<>>
....

---

---

Ahem.... This kind of loop structure must have been copy-pasted from one of Feuerstein's examples of good programing pracztices. :p

Quote:

---

Originally posted by jmodic
Ahem.... This kind of loop structure must have been copy-pasted from one of Feuerstein's examples of good programing pracztices. :p

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No, from METALINK:

Note:60545.1

Actually, the end is like that:

END LOOP;
<< all_done >>
-- Deallocate the device
sys.dbms_backup_restore.deviceDeallocate;
END;

Heh heh heh heh .... :cool:

Quote:

---

Originally posted by jmodic
Heh heh heh heh .... :cool:

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So, what is funny?

Isn't it obvious?

Quote:

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Originally posted by jmodic
Isn't it obvious?

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Very obvious :-)

Thanks for your responses. I just got back from a 4day vacation. Am yet to assimilate what you guys said completely. Will respond later in the day. Inbox is flooded..and have a few fires to put off.

PS : Why did I even bother taking a vacation..@#$$#!!
PPS: Just looked at the responses briefly again..I don't understand, how I would be able to extract the newly backed up archivelogs with an old controlfile? Note: the archivelogs were backed up using RMAN.

Julian,

Quote:

---

OK: if the control file is old, you restore and roll forward to the last archive you have on disk. Even if the control file has no entries of this "new archives" created after the backups, it will allow you to roll past this point. "Recover using backup controlfile".

If you have all the archivelogs on tape, you can restore them to disk, "catalog" them and you will be able to recover.

---

Para 1 - Machine bombed. There are NO archivelogs on disk. All that I have to go by are the hourly RMAN archivelog backups, that are now on tape.

Para 2 - Again, the archivelogs were backed using the RMAN catalog. So it's not easy restoring them, since the catalog itself crashed. So no question of recovering them and re"catalog"ing them.

Hrishy,

Quote:

---

The reason being RMAN always includes the control file in a backup operation that includes file 1 (system data file),regardless of the autobackup setting

so u will be able to recover completely in your case.

---

Yes. But RMAN does NOT include controlfiles when you backup archivelogs. So your code is not applicable. I'll end up with an old controlfile.

Julian - How does your second piece of code/post help the cause?


Thanks for your responses.

Hi

You mention

The target was backed up at 8am this morning


i will use this backupset to extract the controlfile using the script posted above.Once i have the controlfile extracted i can use that controlfile mount the database and ask rman to rollforward the database by applying the archived redo logs.

I hope i am able to clear your doubts.In case you still have trouble i suggest a booj oracle RMAN backup and recovery guide by Robert Freeman it covers some of the scenarios like this

regards
Hrishy

Julian/Hrishy - my fault. Didn't notice the "backup" controlfile bit. I'll have to try it with RMAN. Doesn't seem readily documented in the user guide. Lemme search again..

Quote:

---

Originally posted by Axr2
Julian/Hrishy - my fault. Didn't notice the "backup" controlfile bit. I'll have to try it with RMAN. Doesn't seem readily documented in the user guide. Lemme search again..

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OK; do it in two steps, extract the controlfile via PL/SQL and them roll forward with RMAN.