Re: Oracle Data Guard - Any Opinions?

"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 ;-)

> >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.

> 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).

> >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!

Thanks for your comments & info. Sybrand. Are you using Oracle 8 or Oracle 9 Data Guard?

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 Wed Jul 30 2003 - 21:07:08 CDT