Re: Dataguard setup at DR site
- From: Asif Momen <asif_oracle@xxxxxxxxx>
- To: Oracle-L@xxxxxxxxxxxxx, ksmadduri@xxxxxxxxx
- Date: Sat, 25 Apr 2009 13:03:53 -0700 (PDT)
Dear Kumar,
>> Is it possible to use the cascade standby approach in this scenario?Yes, you
>> can have cascaded physical standby databases (I think you can go up to 9
>> cascaded standby databases)
>> Based on the real world experience, how much of a performance impact would
>> it be if force logging is enabled?
The answer is, "it really depends". In an OLTP environment you would gain
little to no whereas in a data warehouse env you may have huge gains.
You may have nologging operations performed on the primary yet keeping your
standby database in sync.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/scenarios.htm#i1015738
Regards
Asif Momen
http://momendba.blogspot.com
--- On Sat, 4/25/09, Kumar Madduri <ksmadduri@xxxxxxxxx> wrote:
From: Kumar Madduri <ksmadduri@xxxxxxxxx>
Subject: Dataguard setup at DR site
To: Oracle-L@xxxxxxxxxxxxx
Date: Saturday, April 25, 2009, 12:03 PM
List
Our current standby is using the Oracle 8 way of apply archive logs to
standby by manually transfering the files and applying it on standby.
Now we want to build a standby at DR location but we want to use Data
Guard instead of the current method being followed on the Primary
standby.
Is it possible to use the cascade standby approach in this scenario?
Transfer from primary to primary standby (which is the old way of
doing things) > Transfer from primary standby to DG standby
Also in our database current force logging is not enabled because a
senior dba felt it will cause performance issue and it was shelved
even before it was tested. Based on the real world experience, how
much of a performance impact would it be if force logging is enabled?
But databases that have DG running should have this enabled anyway as
this is a prereq.
The documentation says this.
Performance Considerations of FORCE LOGGING Mode
FORCE LOGGING mode results in some performance degradation. If the
primary reason for specifying FORCE LOGGING is to ensure complete
media recovery, and there is no standby database active, then consider
the following:
How many media failures are likely to happen?
How serious is the damage if unlogged direct writes cannot be recovered?
Is the performance degradation caused by forced logging tolerable?
If the database is running in NOARCHIVELOG mode, then generally there
is no benefit to placing the database in FORCE LOGGING mode. Media
recovery is not possible in NOARCHIVELOG mode, so if you combine it
with FORCE LOGGING, the result may be performance degradation with
little benefit.
Thank you for your time
- Kumar
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