Re: offload backup to standby

hrishy wrote:

> Hi All
>
> Suppose i have a 3Tb database on the following version of oracle
>
> a)9iR2
> b)817
> c)7.3.4
>
> In 9i R2 we can use datagaurd and releive the primary database and
> make it available whil the backup window of say 15-18 hours can be
> utilized without disturbing production on the datagaurd database.
>
> I was just wundering can we do anything similar on 817 and 7.3.4
> versions of standby databases ?

Not as such, for the simple reason that the standby databases in those versions could not be opened for business. In 8i, it could be opened read only, but that would mean no DML... and it's not a standby database whilst it is open read only because a read only database can't have redo applied to it (so the replication of redo from primary to the standby is suspended). So you can't be *using* the standby whilst it is acting as a standby.

But there's no reason I can think of, if it's really a major drama, why you can't back up the *standby* databases in those versions, without backing up the primary at all. It's not an approach I'd necessarily recommend, but the standby in all versions (in theory) eventually contains everything in itself that the primary at one point had. So a backup of one is effectively a delayed backup of the other.

That said, the whole premis of the question is suspect, because if it takes 15+ hours to backup your database, you don't backup the entire database at one sitting. That's one of the reasons why we have separate tablespaces. One, two or whatever a night, and if it takes all week to back the lot up, so be it. Provided you retain a week's-worth of archives, it makes no difference to the security of your data.

> Can i create a standby database for 7.3.4 and 8.1.7 and then take a
> hotbackup

In those other versions, the standby database is not active and therefore the concept of hot backup doesn't apply.

>of the secondary databases do a couple of log switches on
> the primary move it to secondary server and backup them as well..
> Has anybody implemented such a scenario.
>
> I am asking this question out of curiosity wundering anybody has done
> this kind of a thing?

Yes, people have. But it's a long-shot, because the security of your data now depends on perfect code in the standby database software components. I would certainly be extremely nervous about it in version 7, though less so in 8i. But even in 9i, the logical standby doesn't work perfectly, so you've got to wonder. It would be better, I think, to have an intelligent backup of the primary database, with the standby as, er, a standby.

Regards
HJR Received on Wed May 05 2004 - 06:56:49 CDT