How to clone DB using RMAN ?

[suhaimi]

Hi all,
I wish to clone a database and keep it synch with primary.
I've tried to use EXP/IMP incremental. The problem is whenever there is a change in a table, it'll export the whole table instead of the changed bit. As a result, I've to import the whole table again so that it'll synch with my primary DB. Futhermore, it takes hours to re-synch since the dump file size is 2GB or more. I've heard that we could do this using RMAN. How do I update merely the changes to my clone DB ???

Rgds,
Suhaimi

 

[sem]

What is the purpose of your clone database? Do you need to read from it or also update?

Regards, Dima

 

[Scunningham99]

you can use the duplicate target database for standby command. This creates a new dbid for your db so you can register in recovery catalogue.


RUN
{
allocate auxiliary channel ch1 type disk;

set until SCN 83426411; #get this by issuing a list backup of database and choose the latest one (highest number from backup set/piece)
set newname for datafile '/user10/oracle/proddata/system01.dbf' to '/user10/oracle/testdata/system01.dbf';
set newname for datafile '/user03/oracle/proddata/az01.dbf' to '/user03/oracle/testdata/az01.dbf';
set newname for datafile '/user06/oracle/proddata/ax01.dbf' to '/user06/oracle/testdata/ax01.dbf';
set newname for datafile '/user03/oracle/proddata/ak01.dbf' to '/user03/oracle/testdata/ak01.dbf';
DUPLICATE TARGET DATABASE TO PROD
logfile
GROUP 1 (
'/user03/oracle/testdata/redo01a.log',
'/user05/oracle/testdata/redo01b.log'
) SIZE 8M,
GROUP 2 (
'/user03/oracle/testdata/redo02a.log',
'/user05/oracle/testdata/redo02b.log'
) SIZE 8M,
GROUP 3 (
'/user03/oracle/testdata/redo03a.log',
'/user05/oracle/testdata/redo03b.log'
) SIZE 8M;
}


HTH

Sy UK

 

[suhaimi]

Hi,
For your info, the clone database acts as a historical db.
We don't want people (mainly report users) to tap into our prod db. We have experienced the worst performance on our prod db server whenever we let them use it. That's the reason we need this historical db badly. We have limited resources ($$). So the cheapest way is to do EXP/IMP, but the drawback is it takes hours. Futhermore, we are using 8.0.4. I believe the "DUPLICATE" option is not available in this version.

Rgds,
Suhaimi

 

[sem]

Do you find it to be cheaper to purchase more Oracle licenses instead of upgrading your hardware? Arguably at least...
Maybe you should optimize your reports by builting agregates in batch mode during idle time. Creating a number of snapshots may resolve an issue. But in any case you should at least catch the biggest resource consumers and try to optimize the most greedy queries.


Regards, Dima

http://seminihin.narod.ru

 

[suhaimi]

Hi Dima,
Your suggestions are accepted BUT how do I use RMAN to simulate the EXP/IMP ??????

Rgds,
Suhaimi

 

[sem]

Do you need to resolve an issue or to use RMAN?
AFAIK you may use RMAN to create stanby database, that is always in the state of recovery using logs from master database. Sometimes you may switch it to read-only mode, but the changes are not applied during that time, so you may see data fixed at the moment it has been opened for reading.

Regards, Dima

http://seminihin.narod.ru

 

[suhaimi]

Sorry....we are using 8.0.4. Opening stdby db in read only mode is available ONLY in 9i if I'm not mistaken.

Rgds,
Suhaimi

 

[sem]

In 8.0.4 snapshots is definitely a good alternative to copying the whole database. You may even create them on another database.

Regards, Dima

http://seminihin.narod.ru

 

[suhaimi]

I've tried to use snapshots b4. It seemed not updating after snapshot refresh. Could you give me the details how I could run the snapshot correctly ?

Rdgs,
Suhaimi