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RE: asking your opinion

From: Freeman Robert - IL <>
Date: Tue, 17 Jun 2003 07:44:04 -0700
Message-ID: <>

See comments below....


Robert G. Freeman
Consultant - TUSC

One browser to rule them all, one browser to find them, One browser to bring them all and into the darkness bind them In the land of Redmond where the shadows lie.

-----Original Message-----
To: Multiple recipients of list ORACLE-L Sent: 6/16/2003 11:14 PM

>> Hi Dear listers,

>> I'd like to ask your opinion about our possible new project.
>> overview; install fatwire for the whole community for web application.
>> no single point of failure, sun servers, oracle.
>> We have more than 10 divisions currently( different department, like
>> arts, dental, enginerring..etc), but we want the flexibility to add
>> more "unit" as the environment changes and grows.

Question 1: database option; what is the pros and cons about physical standby database, logical staandby or RAC? I think the answer should be RAC, right?

You are asking the question without yet really providing the requirements.

The standby database (logical or physical) is there to meet disaster recovery requirements, *NOT* HA requirements. It's need is defined by your SLA's with regards to how much down time can I have, do I need a remote site, do I need to be able to revert to a previous image of my database, etc...etc... For some environments, offsite backups are perfectly satisfactory in this regard, at other sites, you have a hot offsite location, where you run dataguard (standby). So, you need to define your needs before you ask the question.

Specifically regarding logical standby databases, they are a great idea but in my mind they are still new enough (and I've seen a bugs enough) that I don't trust them yet for mission critical application failover. I might consent to using one in combination with at least one physical standby if needs and resources allowed. Still, for right now, if my requirements dictated a standby database, I'd go physical.

RAC, OTOH, is there to meet HA requirements, not DR requirements (unless you can configure a long distance RAC cluster which I have yet to see work really well yet). RAC is an added cost option to Oracle, with it's own set of headaches that may or may not be worth your time and money. Again, it depends on your needs, budget and SLA's. If you need four 9's uptime, then RAC may well be the way to go. If you have a rather stable system, and your users can stand an outage, then perhaps you do not need RAC. Again, you must define the requirements first, then look for the solutions.

>> question 2: Among the questions is whether this is a series of
>> databases for each unit or a central database that is shared by all?
My personal rule about this is that if a given application is going to largely share data with another existing application, and there are no good reasons to separate them into their own databases (for example wildly different SLA's with regards to HA or DR), then I will simply use the same database. This avoids problems with disparate data issues (and saves a bit of memory and CPU).

However if the application is self-contained, or if it uses data feeds from several systems (which is much more frequent in my experience) then it goes into it's own database and we have to decide how we are going to feed it data.

HTH!!! Robert

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Author: Freeman Robert - IL

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Received on Tue Jun 17 2003 - 09:44:04 CDT

Original text of this message