RE: Data Guard vs Streams for a RAC database
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <sjaffarhussain@xxxxxxxxx>, "'Oracle-L Freelists'" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 8 Dec 2010 09:45:55 -0500
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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
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 region
(http://www.oracleracsig.org/)
I blog at
http://jaffardba.blogspot.com/
LinkedIn : http://www.linkedin.com/in/sjaffarhussain
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"Winners don't do different things. They do things differently."
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