Re: Backup en Caliente

From: Brian Peasland <oracle_dba_at_nospam.peasland.net>
Date: Tue, 18 Apr 2006 13:45:59 GMT
Message-ID: <Ixx7Ks.LGJ@igsrsparc2.er.usgs.gov>

> After reading docs, I made several tests and I think that I found my
> error. I'm not sure, but when I tried to recover at a given time
> (recover ... until time ...), I didn't put the exact time (given by the
> backupcontrolfile). If I put the time with minutes and seconds, it
> works.

I'm not sure what you are trying to tell me here. It is unclear to me.

When you use the RECOVER UNTIL TIME command, you specify the time to recover up to. In this doc:

http://download-east.oracle.com/docs/cd/B19306_01/backup.102/b14191/osrecov008.htm#sthref1772

You can see the following:

If recovering to a time, the time is always specified using the following format,
delimited by single quotation marks: 'YYYY-MM-DD:HH24:MI:SS'.
The following statement recovers the database up to a specified time: =
RECOVER DATABASE UNTIL TIME '2000-12-31:12:47:30'

Does that help?

> I suppose that the system does any changes in system.dbf while
> "begin...end backup". In fact, the error refers to system tablespace.
> (Remember that I was trying to recover complete database, simulating a
> total hardware failure, because I have to take a decision about backup
> strategy).

When recovering up to a point in time, the system will look at the SCN in the datafile header from your restored datafile. It will then look for the SCN that most closely matches the time you specified. The system will then apply any changes made to that datafile between the two SCN's. Since you are performing a RECOVER DATABASE, this recovery is applied to all datafiles. The system uses the archived redo logs and possibly the online redo logs for a record of these changes.

You say that you are trying to simulate recovery from a total hardware failure. Does that include recovering the archived redo logs as well?

HTH,
Brian

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Brian Peasland
oracle_dba_at_nospam.peasland.net
http://www.peasland.net

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Received on Tue Apr 18 2006 - 08:45:59 CDT