RE: STANDBY DB - 2 questions

Folks,
This is a good discussion. May be a good question for oracle support. I always wondered why should we need online redo's when standby can not be opened in read/write mode.

Oracle recommends to copy the all files from primary to create the standby database. I wanted to be on the safer side when I created my production standby database seeing all nervousness around about the reliability of this low cost disaster recovery solution. Also , I keep the standby redologs for enabling the graceful switch over and back (useful only for planned maintenance or when all files including redos are available at Primary!) recommended by oracle. I have tested this only on the test installation. I never got the time to experiment without redos at standby. Worth trying.

Did you guys know that Oracle 9i claims to have an enhanced standby database (logical stadby db) which can be opened in read/wirte mode? That will be interesting.
Jyoti

-----Original Message-----
From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of Roby Sherman Sent: Friday, December 15, 2000 6:36 AM
To: Multiple recipients of list ORACLE-L Subject: Re: STANDBY DB - 2 questions

Roby Sherman wrote:

> arun wrote:
>
>> First
>> u do not need logfiles for the standby database since it is not opened
and
>> it is mount state.
>>
> Yes, and how would you propose activating the standby without online
> redo log files to reset? The standby will not pre-create pre-create
> them. You really should have the online redo logs over on the standby
> as well.
>

Allow me to clarify this point further:

Having a base set of online redo logs on the standby are useful for two reasons:
1> If the primary database fails in a manner where the online redo logs are corrupted / unavailable, then you will still need some type of file placeholder for the redo logs on the Standby or the activation process will fail.

2> If the primary database does indeed fail and you can retrieve the online redo logs, they will come in handy in recovering as much of the remaining transactions as possible prior to activation of the standby.

Either way, it makes sense to copy the online redo logs from the primary to the secondary two times. (The first when the standby is being created (to keep some placeholders around), the second when the primary fails (assuming they are available and that they contain redo not yet archived)).

--Roby

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Author: Roby Sherman
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