Re: High Availability -- True 7x24x365

Exactly, you can't make an off-the shelf application really highly available just by using some underlying technology, RAID, clustering, RAC, DataGuard or whatever. Your application has to be planned, designed and built from start with high availability in mind...

If you want 100% availability, hire 3 persons for every task, build three different systems to do the same thing, which are based on different RDBMSes, OSes and hardware, located in completely separated environments and let those redundant employees do the same tasks with their systems all the time ;)

Of course 100% availability can never be guaranteed and this "solution" above introduces human error risk and is extremely costly - and whenever one system is taken down for maintenance, you got to keep some kind of log of operations piling up, to get your system back in sync afterwards again :)

Tanel.

• Original Message ----- From: "Hameed, Amir" <Amir.Hameed_at_xerox.com> To: "ORACLE-L" <oracle-l_at_freelists.org> Sent: Thursday, July 07, 2005 3:18 PM Subject: RE: High Availability -- True 7x24x365

> It becomes even more complex when you are using an application like
> Oracle's E-business suite. During the upgrades/patching, the application
> is unavailable to the end users and it is quite difficult to engineer a
> solution where all transactions could be routed to another database and
> then somehow captured and reapplied to the 11i database after the upgrade.
> We have tried it once in the past but because of the number of tables
> involved (thousands) and the complexity of oracle apps, we were only able
> to provide offline operations to just one part of the business. So, if you
> are using Oracle apps and consider downtime as either scheduled or
> unscheduled then it will be extremely difficult to implement 99.9999%
> availability. We have explored this opportunity extensively and discovered
> that even Oracle Corporation internally shuts down the apps during
> upgrades. Go figure ..

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