Re: RMAN Backups/Recoveries

"Ofer Razon" <orazon_at_012.net.il> wrote in message news:<brl15q$92s$1_at_news2.netvision.net.il>...
> Hi All.
>
> Using Oracle 8.1.7, I am considering the use of RMAN in order to run a
> continous recovered DB, so I`ll do a full recovery once and then, every X
> days I`ll run an incremental recovery for this DB.
> I know that the DB will never be "open". My actual plans are to use PIT
> disks features and open a copy of the database everytime I`ll need it,
> without ruining the recovery process.
>
> At first we considered using a Stand By DB, but then we`ve found that every
> time we`ll add/resize a datafile we`ll have to do it on the standby too, so
> we dropped this idea.

Why is that such a deal-killer? From your subsequent posts, sounds like this is really what you want to do. Sounds like you have hardware that can snap a mirror of the recovering db. You would want to do this while it is in between applying archived logs to the standby db. This is because there is a process called RFS that runs on the standby machine to apply the archived log sent from the primary machine. The primary machine waits for RFS to tell ARCH that it is done applying, before the primary can move on (even if the standby is an optional location). So several things can go wrong if you try to snapshot the recovering db while RFS is applying the log, including slowing down the primary, and splitting off a mirror with an unrecoverable redo log.

I wouldn't have believed it, but I've recently had the experience (on 8.1.7.2 hp-ux 11) that if the Standby platform dies while RFS is running, it can stop the primary from archiving. What is supposed to happen is there is a timeout based on TCP parameters, (which many places set too long, see metalink note 255959.1) but what I saw was that it didn't work at all. This locked up my production database, with no way to switch more than a few logfiles short of a resetlogs. O HA support is still trying to figure this one out for me.

>
> Will RMAN solve me this problem?
> Do you think that it is possible to run in a "continous recovery" as I
> described?
> BTW: I`m couting on the feature that every "incremental recovery" will
> update only the affected blocks in the DB and won`t create the full datafile
> from scratch.

RMAN can be used to create the standby, RMAN can be used to recover a backup. Standby is for continuous recovery.

RMAN can also be used to do the old style hot backup, perhaps in concert with your hardware snapshot ability you can use it to quickly clone (ie, silver third mirror, place all tablespaces in hot backup mode, break mirror, end backups)? How often do you add datafiles, anyways?

>
> Thanks,
> Ofer Razon.

jg

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