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Re: Cold Backups in NOMOUNT Stage

From: Gerry Sinkiewicz <>
Date: Thu, 17 Aug 2006 23:07:06 GMT
Message-ID: <uE6Fg.14170$>

"Brian Peasland" <> wrote in message
> Raaj wrote:
> > Friends,
> > I am fresher in Oracle DBA. I have some few doubts. Pls
> > clarify me.
> >
> > 1) Can we take cold backup in NOMOUNT Stage.
> > At nomount stage only pfile is read and SGA is allocated and
> > background process are started. So to my knowledge, i think we can take
> > backups. Please correct me if i am wrong.
> You can do this if you are using User Managed Backups. But why would
> you? What is the advantage of putting the database in NOMOUNT and then
> performing a cold backup? Why not make your life simpler and just
> SHUTDOWN the database entirely?
> As Frank showed, cold backups with RMAN want the database to be mounted.
> That is so RMAN can read the control files to find the datafile
> locations, etc.
> > 2) How to monitor LOG SWITCH.
> > Is it by monitoring ALERT LOG and by querying V$LOG and
> You can look in your Alert Log or if you are running in archive log
> mode, you can also query V$ARCHIVED_LOG. V$LOG will show you when that
> online redo log was first time that log group was written to.
> > 3) If one of my online redolog is corrupted in which it contains more
> > than half of REDO entries, how can i recover. Is it a nice thing to
> > drop the online log which has more than half of redo entries. How to
> > recover the data ie redo entries in redolog in that case.
> I'm assuming that you have multiplexed your online redo logs. This means
> if one member of a group becomes corrupted, Oracle can use the other
> member. So you should never run into the scenario you described above.
> HTH,
> Brian
> --
> ===================================================================
> Brian Peasland
> Remove the "nospam." from the email address to email me.
> "I can give it to you cheap, quick, and good.
> Now pick two out of the three" - Unknown

As the others have said multplex your redo_logs. At least 2 members in each group and those of course must
be on different volumes/LUNs/disks. Even 2 members on the same RAID 5 volume is not good enough.
If corruption, but more likely loss, occurs the 2nd member will save you from a very embarrassing explaination
on why you just lost a few billion euros worth of data. Received on Thu Aug 17 2006 - 18:07:06 CDT

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