Re: Cold Backups in NOMOUNT Stage

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$LOG and
> V$LOGFILE.
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

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Brian Peasland
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