RE: Data Guard vs Streams for a RAC database
Date: Wed, 8 Dec 2010 09:45:55 -0500
Message-ID: <D44F1FB8E50740C8BE49265F7DBFD82F_at_rsiz.com>
The reasons why a physical recovery server is the superior solution for your stated requirement are that it has the fewest moving parts, the moving parts it does have are the simplest, the technology is thoroughly proven, and you can even configure a test protocol to establish that your recovery server is openable and complete.
In fact I would suggest that doing something with RMAN would be more competitive with a physical standby than streams in your case where a place to failover to in an incident is the primary purpose.
This is not a statement against Oracle's streams and goldengate implementations of replication, but rather the fitness for purpose of the technological tool. Physically applying the actual data block changes required is simplest and most lightweight way to get a full copy. (Snapshots of course requiring the original to survive to make up a complete whole.)
Whether you use an official Dataguard implementation or roll your own (a physical standby server requires no more than continuous physical recovery after all, and has a failure rate better than DNA since at least 6.0.37) this is very reliable. If you do roll your own remember to make provision for preventing nologging operations on the original (or reinstantiating the affected tablespaces within your surety window) as well as creating any new data files on the target before the redo that applies to them arrives.
If you have thoughts about OPENING the target concurrently with it remaining the standby, then all the various arguments about active dataguard versus selective replication or streams somewhere apply and you have a lot of legitimate horses back in the race for determining the best fit for your purpose.
Of course the alternative of temporarily suspending application of redo do
the target, shutting it down, doing a full copy with an open RENAME so you
can test, and then resuming the target it was fully described in 1995
(Getting the Most of your Standby Recovery Server), and is far too long for
a list post.
Good luck! It sounds to me as if you are thinking clearly about your problem!
mwf
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]
On Behalf Of Syed Jaffar Hussain
Sent: Wednesday, December 08, 2010 8:30 AM
To: Oracle-L Freelists
Subject: Data Guard vs Streams for a RAC database
Good day everyone,
We are in need of preparing a backup server for one of the business critical RAC databases at our company. Since the DRC setup will take some considerable time, application owner requested to maintain a backup database server (active) for the database to be able to survive from any scary incidents. Although my vote goes to Data guard configuration, we would like to choose the best and a very light weight option to fulfill the requirement. Any pros and cons or comparision between these two would be highly appreciated.
-- Best Regards, Syed Jaffar Hussain Oracle Certified Master (10g) http://www.oracle.com/technology/ocm/shussain.html Co-author Oracle 11gR1/R2 RAC Handbook http://www.packtpub.com/oracle-11g-r1-r2-real-application-clusters-handbook/ book Oracle ACE http://apex.oracle.com/pls/otn/f?p=19297:4:4640302666204919::NO:4:P4_ID:186 OCP 8i,9i,10g & 11g DBA RAC Certified Expert Official Oracle RAC SIG Representative for Saudi Arabian regionReceived on Wed Dec 08 2010 - 08:45:55 CST
(http://www.oracleracsig.org/)
I blog at http://jaffardba.blogspot.com/ LinkedIn : http://www.linkedin.com/in/sjaffarhussain -------------------- "Winners don't do different things. They do things differently." -- http://www.freelists.org/webpage/oracle-l