Re: RMAN Recovery Question

ame..._at_iwc.net wrote:
> This page: http://www.dizwell.com/html/ba%adcking_up_redo.html,
> basically confirms what I was saying, which is that the online log is
a
> weak point in the Oracle recovery process.
>
> If I am using RMAN and need to recover, how does RMAN know about the
> current online log if it has not been archived?
>
> Or, does the database take care of that after RMAN is finished
> recovering?

RMAN doesn't change the fundamental rules of backing up and recovering an Oracle database. You don't backup online redo logs -- not with RMAN and not if you are doing your own backups with some other tool. This is why you need to multiplex your redo logs (and don't think that simply having your logs on mirrored disks is enough). You need to have multiple members in your log groups. This way, Oracle is writing independently to each log (and of course you are putting those different logs on different disks ,controllers etc.) You want to protect yourself from losing your online logs (in the same way you want to avoid losing your controlfiles -- this is why you have multiple copies of those, too).

If you are truly trying to give yourself ultimate protection of your data, then you need to look at standby databases and "maximum" protection mode of DataGuard (whereby a transaction is not committed on the primary database until the redo information is written both to the primary and the standby). In this manner, even if you lose your entire primary site, you won't lose committed data.

Of course there are costs and complexity to all levels of protecting your data which is why you need to understand the various scenarios and find out how much data loss you can live with compared to the costs of protecting it. Received on Thu Apr 14 2005 - 11:00:51 CDT