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From: Seema Singh <>
Date: Tue, 29 Jun 2004 17:11:03 -0400
Message-ID: <>

Thanks Carel!
PSB and LSB features available in 9i and later. What version are/is your customer you on? :8163
OS? : Sun solaris
How much is 'minimum outage'? : 2hrs.
>How much data-loss is allowed? : theoretically ZERO
Is it abig database? : 30 to 40gb but expecting more growth. What are the arguments against Standby/Data Guard? :They don't want.


>From: Carel-Jan Engel <>
>Date: Tue, 29 Jun 2004 21:37:46 +0200
>At 03:12 PM 6/29/2004 -0400, you wrote:
> >Hi,
> >I have setup production database full replication on seconday box in
> >READ-ONLY MODE.Users are accessing the box boxes for DMLand select on
> >PRODUCTION and select for secondary box.In case of disaster (suppose
> >production database are having problem like disk failure ,controller
> >etc) can I make READ-ONLY MODE database to READ-WRITE mode.
> >
> >Here is my problem:
> >I have 2 identical box name db01 and db02.On db01 production instance is
> >running.I want to use processing capacity of db02 24x7.I want to setup
> >replication in such a way that in case of disaster (failure of db01) can
> >switch to db02 with minimun outage.
> >Client don't want standby or dataguard solution.

>What version are/is your customer you on? OS? How much is 'minimum outage'?
>How much data-loss is allowed? Is it abig database? What are the arguments
>against Standby/Data Guard?
>On Oracle 7 I implemented a home-grown DR configuration based on triggers.
>This was usefull for an underused database on an overpowered serverd.
>Basically there was a small table storing the actual state of the database.
>It was standby all the time, forced so by some custom code in the dbstart
>script. Pre-insert/update/delete triggers prevented anyone from changing
>colums, except the replication-user. Replication was performed
>asynchronously. Failover meant just changing the 'active state' in the
>special table and go for it.
>Later, in 8i, this was migrated to an Advanced Replication solution. This
>site is out of sight now.
>Data Guard with Logical Standby _can_ help, but with quite a few
>constraints. I've setup a similar configuration, however, There 'was a
>Physical Standby for DR, and a Logical Standby for reporting. I wouldn't go
>for the LSB/DR combination on 9i. For 10g I haven't dobe enough
>investigation to give a clue. It might be better. When you are on processor
>licenses, you might be able to run the query/LSB on the same server as the
>DR/PSB database. It depends on the amount of redo that's created, and how
>much the server suffers from the recovery on PSB _and_ LSB together with
>the planned reports on the LSB.
>I think it is technically spoken possible to create a replication mechanism
>to synchronyze db01 and db02. However, don't underestimate the amount of
>work for creating and testing such an environment, not to mention
>monitoring, management and maintenance to keep the thing up, running,
>accurate, etcetera....
>Regards, Carel-Jan
>If you think education is expensive, try ignorance. (Derek Bok)
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Received on Tue Jun 29 2004 - 16:08:07 CDT

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