Home » RDBMS Server » Backup & Recovery » Seeking info on rman restore and recovery process (Oracle 10.2.0.4 RAC on RHEL 5.1)
Seeking info on rman restore and recovery process [message #493241] Mon, 07 February 2011 00:55 Go to next message
NandKumar
Messages: 92
Registered: June 2007
Location: v$hyderabad
Member
Hi experts,

I have a doubt regarding the process the RMAN follows for restore and recovery of the database.

My Level 0 full backup completes on Saturdays at around 11 am after taking 8 hours (It starts at 3am).
On Sunday, I ask RMAN to restore (on a different box) till Saturday 11:30 am.
Then, after the restore is successful, I recover it till 11:45 am.

The recovery also goes fine and Iam able to clone to test box.

My questions are:

Till what time is the database restored? I assume its till 11 am since the L0 backup finishes at 11 am though I have asked it to restore till 11:30 am

During the recovery, ONLY the archives generated between Saturday 3 am and till the time i asked for recovery (Saturday 11:45 am ) are required.

But, checking the recovery log file, i was surprised to see that RMAN has restored archive files starting from Friday 9:30 pm (Much before the time the Level 0 backup even started).

Can anyone throw some light on this....why does RMAN require the old archive log files.

I assume, Your relies will help me in understanding the backup and recovery process in greater detail.

Thanks in advance
Nand
Re: Seeking info on rman restore and recovery process [message #493244 is a reply to message #493241] Mon, 07 February 2011 01:06 Go to previous messageGo to next message
hkchital
Messages: 128
Registered: September 2008
Location: Singapore
Senior Member
Your "SET UNTIL SATURDAY 11:30" would have instructed RMAN to
a. Restore the latest backup as of upto that time -- e.g. if datafiles had been backed up between 11:00 and 11:29, they have been restored. In your case, the backup that ended at 11:00 on Saturday was restored.
b. Recover the database until 11:30. This means that RMAN requires, restores and applies all the ArchiveLogs that have transactions upto 11:30.
However, as you specified an "UNTIL SATURDAY 11:45", the Recover phase actually went upto 11:45
(Thus yours is an example of SET UNTIL specified differently for the RESTORE and the RECOVER phases).


>archive files starting from Friday 9:30 pm
How did you identify these files ? Based on FIRST_TIME or COMPLETION_TIME in V$ARCHIVED_LOG ?
Note that an ArchiveLog may contain Transactions of 9:30pm of Friday right upto 3:01am of Saturday. Such an ArchiveLog would be required for the Recovery.


Hemant K Chitale
Re: Seeking info on rman restore and recovery process [message #493248 is a reply to message #493244] Mon, 07 February 2011 01:30 Go to previous messageGo to next message
NandKumar
Messages: 92
Registered: June 2007
Location: v$hyderabad
Member
Thanks hkchital,

Quote:
How did you identify these files ? Based on FIRST_TIME or COMPLETION_TIME in V$ARCHIVED_LOG ?


Yes, I used the v$archived_log and found the first_time, next_time and completion_time. Here are those values:


FIRST_TIME NEXT_TIME COMPLETION_TIME
---------------- ---------------- ----------------
2011-02-03-21:50 2011-02-03-22:50 2011-02-03-22:54

Quote:
Note that an ArchiveLog may contain Transactions of 9:30pm of Friday right upto 3:01am of Saturday. Such an ArchiveLog would be required for the Recovery


How can we identify those archive files. Will the Completion_time in v$archived_log denotes this information ?

Thanks
Nand
Re: Seeking info on rman restore and recovery process [message #493443 is a reply to message #493248] Tue, 08 February 2011 00:13 Go to previous messageGo to next message
hkchital
Messages: 128
Registered: September 2008
Location: Singapore
Senior Member
Did the file need to be applied during the RECOVERy ?
Check the alert.log if you don't have the RMAN log.


Hemant K Chitale
Re: Seeking info on rman restore and recovery process [message #493453 is a reply to message #493443] Tue, 08 February 2011 02:05 Go to previous message
NandKumar
Messages: 92
Registered: June 2007
Location: v$hyderabad
Member
Hi Hemant,

Thanks a lot for your responses......

We generally separate the restore and the recover steps into different scripts.

Now coming to the yesterday's issue....I was unable to check all the rman related logs yesterday ( My mistake Sad )

Now I came to know that there were errors reported in the restore log file as well. One of the backup piece was corrupted and could not be read. Thus, though it reported that restoration was done till Level 0, some datafiles couldnt have been restored completely.

Now during the recovery, the old Level 1 differential and cumulative backups were used to restore the datafiles which were part of that corrupted backup piece. After that archives files were restored. But this recovery failed due to insufficient disk space in archive location.

It was initiated again and all those remaining archive files were restored and recovery completed successfully.


Thanks a lot for your valuable time and insights.


-Nand

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