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Re: High-availability database question !!!!

From: Mogens Nørgaard <>
Date: Wed, 25 Jun 2003 07:57:48 -0700
Message-ID: <>

  1. RAC can duplicate your instances/nodes. But you still have only one database.
  2. One database means un-availability whenever you have to apply a patch or upgrade the database. No online patches available. No rolling upgrades.
  3. Dataguard needs to have exactly the same version (down to patch level) on the two (or more) databases. So that just means two databases down if you have to patch or upgrade. That might come as a surprise to some people, but there's basically no 25/8/370 availability with Oracle unless you either specify downtime as something else or don't patch/upgrade at all.
  4. Logical stuff like replication, logical Dataguard, Shareplex from Quest and others can get around the "everyhing-has-to-be-the-same-version" by using logical replication of some sort - some faster, some slower.


Jackson Dumas wrote:
<blockquote type="cite"
  Goodday all

We have cutomer who is having a database which should be available 24x7.
Now we can't get even a maintenance time to do the database. We tried on several occasion but nothing happens. Now they want us to provide them with a solution to be able to work on "another database" if we need to do maintenance. Could you guys come up with some ideas what we can offer them. Is there any other alternatives besides replication and standby database. Currently the system is running as a package in a cluster environment, HP-UX, so when we go replication route possibilities are that we might have to forget about high-availabilty cluster environment due to things like disk space and memory for switching over during failure. Neither do the standby database a good option in a situation where you'll needing a longer downtime.

Please help.


Junior DBA

On Tue, 24 Jun 2003 08:19:18 -0800 ([EMAIL PROTECTED]) wrote:      

    Hi there,

I got a question on log. If my program crashes, can I check some log        

  to see what      

    recent transaction is? It will give me a big help on trouble        



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