Re: URGENT: Hot Standby Graceful failover and failback

Hello Leng,

> 1. create a hot standby from a primary database
> 2. activate the hot standby
> 3. shutdown the new primary and made a backup of the new primary
> database
> 4. restart the new primary, created a table and create a standby
> controlfile
> 5. shutdown the new primary
> 6. restore from backup created in step 3, and replaced the current
> control files with the standby controlfiles created from stop 4
> 7. mounted the database in standby mode again
> 8. tried to activate the new standby database but it failed with
> ORA-1152 and ORA-1110 complaining that the system.dbf is not restored
> from a sufficiently old backup.

I thought you were supposed to do a hot backup of a new primary and restore it to the old primary. After that, mount the old primary as a new standby.

> Argh! How do we have a continuous failover and failback scenario? Any
> help would be greatly appreciated.
>
> I've just discovered Lawrence To's article on Graceful Switch Over and
> Switch back as well. The following from page 11 scares me:
>
> "Graceful switchover and switchback are not possible when the
> production database's online redo logs are not accessible.
>
> A graceful switchover and switch back is NOT possible whenever a
> production database or standby database executes one of the following:
>
> - alter database open resetlogs or
> - alter database activate standby database (which does an implicit
> resetlogs operation)"
>
> HUH??? There are certainly times when we have to do a resetlogs. One of
> the problems our Unix boxes have at the moment is a redo log corruption
> so there are not choices but to resetlogs. So what does this all mean?
> That if we resetlogs we can't ever have continuous failover and
> failback?

Yes, it is correct. If you reset logs or loose the redo logs, forget about "graceful switchover".

> ARGH!! What am I dealing with here!
>
> I need a holiday from this crazy scenario!
>
> Ok, please let me know if you've had any success with what I'm
> describing here. Am I aiming for the impossible? Surely not!
>

I am sorry to admit, but you are :-)
So far at 8.1.7 we have only the "graceful switchover", awfully well described in Lawrence To's article.

HTH,
Michael

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