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From: Orr, Steve <>
Date: Wed, 30 Jun 2004 10:42:40 -0600
Message-ID: <>

> I wouldn't go for the LSB/DR combination on 9i.=20
Why not? I was just getting ready to try this exact same thing. (i.e. implement a Physical standby and a logical standby.)

Steve Orr
Bozeman, Montana

-----Original Message-----
[] On Behalf Of Carel-Jan Engel Sent: Tuesday, June 29, 2004 1:38 PM

At 03:12 PM 6/29/2004 -0400, you wrote:
>I have setup production database full replication on seconday box in=20
>READ-ONLY MODE.Users are accessing the box boxes for DMLand select on=20
>PRODUCTION and select for secondary box.In case of disaster (suppose=20
>production database are having problem like disk failure ,controller=20
>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=20
>is running.I want to use processing capacity of db02 24x7.I want to=20
>setup replication in such a way that in case of disaster (failure of=20
>db01) can we switch to db02 with minimun outage. Client don't want=20
>standby or dataguard solution.


What version are/is your customer you on? OS? How much is 'minimum outage'?=20
How much data-loss is allowed? Is it abig database? What are the arguments=20
against Standby/Data Guard?

On Oracle 7 I implemented a home-grown DR configuration based on triggers.=20
This was usefull for an underused database on an overpowered serverd.=20 Basically there was a small table storing the actual state of the database.=20
It was standby all the time, forced so by some custom code in the dbstart=20
script. Pre-insert/update/delete triggers prevented anyone from changing

colums, except the replication-user. Replication was performed=20 asynchronously. Failover meant just changing the 'active state' in the=20 special table and go for it.

Later, in 8i, this was migrated to an Advanced Replication solution. This=20
site is out of sight now.

Data Guard with Logical Standby _can_ help, but with quite a few=20 constraints. I've setup a similar configuration, however, There 'was a=20 Physical Standby for DR, and a Logical Standby for reporting. I wouldn't go=20
for the LSB/DR combination on 9i. For 10g I haven't dobe enough=20 investigation to give a clue. It might be better. When you are on processor=20
licenses, you might be able to run the query/LSB on the same server as the=20
DR/PSB database. It depends on the amount of redo that's created, and how=20
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=20
to synchronyze db01 and db02. However, don't underestimate the amount of

work for creating and testing such an environment, not to mention=20 monitoring, management and maintenance to keep the thing up, running,=20 accurate, etcetera....

Regards, Carel-Jan

If you think education is expensive, try ignorance. (Derek Bok) = =3D=3D=3D=20

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Received on Wed Jun 30 2004 - 11:46:03 CDT

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