View Full Version : Maintenance work on Standby Database

11-02-2011, 02:49 AM
This is more of a 'is this posible' type question. We are evaluating DVisit at the moment and so far it is working well (once we got it installed) and I was wondering. One of my DBA tasks that I do periodically is rebuild all the indexes and also use a tool from Quest Software (called Space Manager) to, in effect, 'defrag' the tables to make them contiguous and also to fix any chained rows etc.

To effectively do this I would like to take the database 'offline' which is very difficult in our organisation as we have sites in China, USA/Mexico and Europe which means we have a 24/7 operation.

In the past I have tried to do the work on a Sunday UK time but there are still users on the system working the weekend shift.

As I read the manual, to do this kind of work on the Standby database would mean bringing it up as a Primary database otherwise it is only accessable in a Ready Only mode.

Ideally, I would like to do this work on the Standby database, then switch the logging on again so that any changes made on the Primary database can be applied. Then I would do a graceful switchover, do the same work on what was the Primary database and then switch back. I know that rebuilding the indexes gets transferred but it has issues if a user has the table open at the time I am trying to rebuild them.

I don't think that this is possible with the setup but would like to seek your opinion on the feasibilty of this.

Many thanks in advance for any assistance you can give.

Oracle 11g databases on Red Hat Linux 5 servers.

Richard Chambers
Worldmark UK
East Kilbride

Arjen Visser
11-02-2011, 02:38 PM
Hi Richard,

One of the limitations with a physical standby database (and this includes Data Guard and Dbvisit Standby) is that only 1 database can be the primary database at a time. If you bring up both databases as primary databases, then you have lost the link (same DBID) between the 2 and they cannot be kept in sync any more.

So it is not possible to bring up the standby database as a Primary database while your users are continuing to work on the existing Primary database, and then bring the 2 databases back in sync.

You can reverse the roles with Graceful switchover, but it still means that only 1 database can be the primary database, and the other must be the standby database.

So unfortunately the scenario you have described is not feasible.

Kind regards, Arjen

11-03-2011, 12:52 AM
OK Thanks. I had a feeling that was the case.