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Re: DR and reporting server

From: Carel-Jan Engel <>
Date: Wed, 07 Jul 2004 09:04:46 +0200
Message-Id: <>

What do you want de reporting database to contain: All data current up to and including the last transaction of the primary, or will a daily refresh do the job? (This question is just about reporting requirements, not about availability/recoverability/data loss).

Referring to your previous post: LSB is there in 9i, but keep in mind that recovery of the transactions will only start _after_ a log-switch, even in maximum protection/maximum availability mode. Both modes will write your transaction synchronously to the Standby Redo Logfile, but not apply them instantly. So, reporting is always behind for a varying period of time. On the other hand, you can have your reporting database opened read-only, and switch it to recovery mode every night. Reporting will then be available through the day, just not including the transactions of the current day. DR will first recover the database up to the last transaction, and then bring up the database.

I found LSB rather instable, not suitable for DR (at least in 9i). For reporting it can be OK, depending on the datatypes you use.

When configured properly (listeners on both servers and tnsnames on clients) you can setup TAF (Transparent Application Failover). This will automatically reconnect the clients to the standby, after a switchover/failover.

When you need reporting up to the last transaction, 10g might help you. Still haven't found time to test, but the new DG feature of instant apply should circumvent the delay up to the logswitch.

Regards, Carel-Jan

If you think education is expensive, try ignorance. (Derek Bok) ===
At 01:35 AM 7/7/2004 -0400, you wrote:
>I have 2 db servers named DB1 and DB2.DB1 is as Primary db server and db2 is
>secondary server.I want to setup the server like followings.In case of
>disaster I can use db2 as primary servers by changing application
>configuration files on application box ,means DB2 should have read and write
>both features.In day to day basis we want db2 for reporting purposes.Which
>method would be best way to do this? If any good stuffs you guyes have
>please also suggest.ANy comments and suggestions are most welcome.
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Received on Wed Jul 07 2004 - 01:55:00 CDT

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