Re: 9iR2 Logical Standby

From: Mark Bole <makbo_at_pacbell.net>
Date: Sun, 14 Nov 2004 19:22:38 GMT
Message-ID: <2gOld.41764$QJ3.30476@newssvr21.news.prodigy.com>

Access wrote:

> "Mark Bole" <makbo_at_pacbell.net> wrote in message
> news:lZtld.41472$QJ3.35225_at_newssvr21.news.prodigy.com...
> 

>>Pete's wrote:
>>

[...]
>>>Questions:
>>>Has anyone ever setup a logical standby for only a couple tables into
>>>another database?

[...]
>>
>>Warning: a logical standby used for this purpose should not be
>>considered an integral part of a disaster recovery plan (that is, don't
>>think of trying to switch over to it if your primary fails).
>>

> 
> Regarding this last paragraph : why not ?
> 
> 

Because your original scenario, the one I was responding to, involves "only a couple of tables". For production switchover or failover purposes, you need the standby to be as identical as possible to the primary at the time of the role transition. This means not only ALL tables but everything else too.

According to the documentation, "a logical standby database can be used concurrently for data protection and reporting". But that means some compromise for one or both functions. For a database that is at the core of a business, I recommend a physical standby strictly for disaster recovery and a separate logical (or physical) standby for offloading reporting from the primary. The former will not normally incur any additional (Oracle) licensing costs, while the latter will.

Also, in version 9i, the new logical standby feature has sufficient bugs and unsupported data types that it typically wouldn't be a good choice for high-quality disaster recovery (haven't used the 10g version yet, but I suspect it's improved).

-Mark Bole Received on Sun Nov 14 2004 - 13:22:38 CST