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Dataguard vs RAC [message #405232] Wed, 27 May 2009 02:20 Go to next message
lodopidolo
Messages: 3
Registered: May 2009
Junior Member
I to every body.

This is my first question in this forum.

Is possible make a RAC with private storage and not with share storage?

I explain my situation. I have two buildings and I want to put one Oracle Database Server in each one. These two buildings are connected using a 100Mb optical net over ATM but we are going to migrate to one gigabit net. All traffic between buildings is made by this network but I can guarantee any transfer rate I need. I want replicate then information in both server to prevent a possible collapse of the building SAN (there is a SAN in each building).

One solution is make a data guard configuration, but I don't want put one of these server in standby. I want all server up and resolving customers request. Then I thought in mixture of both: Data replication of data guard, and service availability of RAC. Then is necessary private storage por each node.

Is possible a RAC or I must make a data guard?
Re: Dataguard vs RAC [message #405257 is a reply to message #405232] Wed, 27 May 2009 03:56 Go to previous messageGo to next message
Mahesh Rajendran
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If you are talking about real time data and serious business, RAC has to be in shared storage.
>>Is possible a RAC or I must make a data guard?

There are other questions that should be addressed.
In most cases, RAC is not necessary at all.
As you have already noted, RAC and DG provide High availability in very different levels. RAC without a standby like arrangement provides very little HA solution.
If your business does a very high volume of transactions, RAC will help.
If the volume of data is high and you want to separate services (reporting for example), DG Standby will help.
DG can be used for dual purpose. For standby and for read-only reporting. Data replication is just a base for DG and you can do much more with replicated data.
If you would just like a replicated site and do not worry about and ideal standby-like environment, you can just use streams.
So it all depends on nature your your system.

Regards

Re: Dataguard vs RAC [message #405272 is a reply to message #405257] Wed, 27 May 2009 04:54 Go to previous messageGo to next message
lodopidolo
Messages: 3
Registered: May 2009
Junior Member
Mahesh Rajendran wrote on Wed, 27 May 2009 03:56
about real time data and serious business, RAC has to be in shared storage.

Ok. It isn't a real time o serious buniness. I only want a another database server in other place serving to all user or balancing with the other server.

Mahesh Rajendran wrote on Wed, 27 May 2009 03:56

RAC without a standby like arrangement provides very little HA solution.
... you want to separate services (reporting for example), DG Standby will help.
DG can be used for dual purpose. For standby and for read-only reporting.


Well, I don't want a read-only system. I want my system run like a RAC, but with some DG characteristics (separate storage for node). Then it could be an HA system.

Mahesh Rajendran wrote on Wed, 27 May 2009 03:56

If you would just like a replicated site and do not worry about and ideal standby-like environment, you can just use streams.



With Stream I could have two identically system, but really these are two separated system. There isn't unique ip for both and unique administration point, isn't it?

Thanks!
Re: Dataguard vs RAC [message #405315 is a reply to message #405272] Wed, 27 May 2009 06:17 Go to previous messageGo to next message
Mahesh Rajendran
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Registered: March 2002
Location: oracleDocoVille
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If you want to do load balancing, you need to use RAC. I would rather rely on RAC instead of other LBS (load balancing switch) for database.
>> Well, I don't want a read-only system.
In 11g, Oracle logical standby can be opened up for read-write (with some restrictions).
Quote:


A logical standby database contains the same logical information as the production database, although the physical organization and structure of the data can be different. The SQL apply technology keeps the logical standby database synchronized with the primary database by transforming redo data received from the primary database into SQL statements and then executing the SQL statements on the standby database. This makes it possible for the logical standby database to be open read-write and accessed for queries and reporting purposes at the same time the SQL is being applied to it.

http://www.oracle.com/technology/deploy/availability/htdocs/DataGuardOverview.html

>>I want my system run like a RAC, but with some DG characteristics (separate storage for node)
As said before, that is NOT possible. RAC needs shared storage.
Re: Dataguard vs RAC [message #405435 is a reply to message #405315] Wed, 27 May 2009 13:46 Go to previous message
lodopidolo
Messages: 3
Registered: May 2009
Junior Member
Ok, thank you very much Mahesh Rajendran. Like you say, I think my best configuration is a Data Guard.
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