Re: Simulating dataguard maximum availability protection mode in Oracle 9i or 10G standard edition

From: Mark Bole <makbo_at_pacbell.net>
Date: Mon, 23 Aug 2004 15:01:02 GMT
Message-ID: <OEnWc.11232$Uk7.2602@newssvr29.news.prodigy.com>

Howard J. Rogers wrote:

> Prem K Mehrotra wrote:
>
>

[...]
>

>>2.    I know Oracle Data Guard is not provided in standard edition, but
>>standby database can still be implemented since Oracle 7.3.x. My
>>question is can standby redo logs be created in standard edition
>>(Oracle9i or 10G) using "alter database  standby logfile …".

>
>
> A very good question, to which the answer is (probably, because I don't have
> a database to hand to test it) almost certainly not. A standby logfile is
> only meaningful when LGWR is going to ship redo to the standby site. LGWR
> can only be configured to do that by using the LOG_ARCHIVE_DEST_n
> parameters. Those parameters are only configurable in Enterprise Edition.
>
> So even if you are allowed to create a standby log in Standard Edition, they
> can't actually be used for anything. Which is why I earnestly hope and
> expect that you won't be allowed to create them in the first place.
>
>

>>Can 
>>maximum availability protection mode be simulated? Can database be
>>opened in read only mode for reporting in physical  standby?

>
>
> Yes to the open in read only mode question. It's been do-able since 8i.
>

[...]

With or without DataGuard (Enterprise Edition), you can implement manual (user-managed) recovery for a physical standby. This means write your own scripts to copy archived redo logs to the standby site and then recover the standby database using them. This would only simulate "maximum performance" mode.

"maximum availability mode" and "open read only for reporting" are conflicting goals. If you want to roll forward your physical standby manually say, once every 24 hours, and then open it for read-only reporting each day, that is very reasonable and achievable with Standard Edition (assuming you can write good scripts). To paraphrase Howard's comment, you'll pay one way or another.

--Mark Bole Received on Mon Aug 23 2004 - 10:01:02 CDT