Re: Oracle Data Guard - Any Opinions?

Comments embedded

"Richard" <qaz1521_at_hotmail.com> wrote in message news:<bg9tkd$s5v$1$830fa7a5_at_news.demon.co.uk>...
> "Sybrand Bakker" <gooiditweg_at_sybrandb.demon.nl> wrote in message
> news:io3giv0q4jkk2ctmmg98b7v4668ggn7462_at_4ax.com...
> > On Wed, 30 Jul 2003 18:53:24 +0100, "Richard" <qaz1521_at_hotmail.com>
> > wrote:
> >
> > >I've been considering using Oracle Data Guard to provide disaster
> recovery
> > >for a number of Oracle 9 databases. The documentation makes it look
> quite
> > >promising but I'm seeking unbiased opinions from users who have
> experience
> > >of the product. In particular: -
> > >
> > >1 Is it reliable? I've had disappointing experiences with Oracle
> software
> > >before.
> > >
> >
> > It is. 'Disappointing experiences' usually result from badly
> > architectured databases, caused by ignoring manuals
>
> This has not been my experience - but I've always been fortunate to work
> with developers & designers who are very competent. You clearly
> weren't an early adopter of Oracle 6 ;-)

You clearly never used Oracle in the days when you had to relink the sw for any change to the SGA and to specify a hexadecimal starting address. 5.1.17 and 5.1.22 here. I remember only one Oracle 6 release with problems, but most of the problems I was experiencing came from hardware malfunction.
>
> > >2 How much flexibility do you have in the choice of operating
> > >system/hardware/oracle version? The documentation seems a bit vague on
> > >this. I understand the operating system needs to be from the same
> > >manufacturer, solaris -> solaris, Linux -> Linux and so on but how close
> do
> > >the versions have to be?
> >
> > They need to be identical.
>
> Are you sure? The manual says that only the database release needs to be
> identical. It also says that the operating system release levels can be
> different but I'm not sure how different.

You wouldn't better bet on it.
>
> > Also, does running the standby on a much smaller
> > >machine to provide core services in an emergency work well?
> > >
> >
> > Running the standby on a much smaller system would be a stupid idea,
> > unless you want to shut part of your user community out.
>
> Financial constraints prohibit the construction of a duplicate server. A
> smaller system
> that can provide a reduced set of core functions while the primary server is
> being fixed
> therefore seems eminently suitable to us. From the manual, it seems that
> you can't write to
> the standby database anyway, even if you wanted to, so surely it wouldn't
> need to be as powerful as the primary if it's only dealing with read
> operations (no locking or constraint validation etc).

You have standby database to make sure you actually *CAN* switchover, with *ALL* your users! Why would you use it anyway? If you have a much smaller system for standby be aware of angry users and/or users you can't service, because you don't have the capacity. Please reread the docs and rethink your strategy.
>
> > >3 How does licencing work? If the standby database can only be used when
> > >the primary is unavailable, will one licence cover both servers or do
> they
> > >have to be licenced separately?
> >
> > They will have to be licensed separately. Also, you seem to think the
> > standby database isn't functioning when used as a standby. This is
> > definitely not true.
>
> Certainly it's functioning, but my understanding is that you can only read
> from a standby's target tables (you can't write to them) and you can't
> access a physical standby at all unless you stop recovery. If Oracle demand
> a full licence for this functionality then surely they are ripping us off!

Licensing questions are best being addressed by talking to a salesrep. Strange so many people evidently don't *want* to do that. However, would you expect Oracle wouldn't charge you anything for that second server? (Or Microsoft for that matter)
>
> Thanks for your comments & info. Sybrand. Are you using Oracle 8 or Oracle
> 9 Data Guard?
>

Using 8i standby
> Regards,
>
> Richard
>
> > Also it is the numbers of CPUs that count.
>
>
>
> > >Thanks for any advice,
> > >
> > >Richard
> > >
> >
> > Sybrand Bakker, Senior Oracle DBA
> >
> > To reply remove -verwijderdit from my e-mail address
Received on Thu Jul 31 2003 - 03:07:03 CDT