RE: Standby redo logs
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <nassyambasha@xxxxxxxxx>, <justin@xxxxxxx>
- Date: Thu, 31 Jul 2014 12:10:12 -0400
Good thread.
One additional point: SOMETIMES a standby is configured with an intentional lag
in the application of the redo as a protection against logical corruption of
your database by any of programming error, hacking attack, insider malfeasance,
<and more than I can think of>. In that case lacking standby redo logs is
useful to prevent accidentally starting the lagged (possibly remote) version of
the database.
Another way to achieve this is flashback of some type, but a lagged standby
*might* be easier to secure from outside attack. Combined with capture of the
raw inbound transaction information, this essentially gives you a time machine.
Having a time machine handy is very useful.
(Please notice none of this contradicted any of the very good suggestions about
various ways of keeping things as close to zero loss as possible with varying
levels of overhead. It merely raised a possibility regarding a different goal
for the standby. The neat thing is that you can have both when that is the
right thing to do.)
mwf
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Nassyam Basha
Sent: Thursday, July 31, 2014 2:23 AM
To: justin@xxxxxxx
Cc: napacunningham; oracle-l-freelists
Subject: Re: Standby redo logs
Yes, I forgot to add that point regarding data loss. There is no such zero data
loss with maximum performance. But if you configure FAST SYNC then you can get
almost and maximum zero data loss with maximim performance until unless rare
situations.. its called catastrophic failure.
On Thu, Jul 31, 2014 at 8:53 AM, Justin Mungal <justin@xxxxxxx> wrote:
Be careful with your wording, because even with standby redo logs you can't
ensure zero data loss unless you're running in maximum protection mode.
I would recommend configuring standby redo logs because instead of applying
redo in batches as archive logs arrive at the standby, you can use real-time
apply (requires standby redo logs) to stream redo continuously to the standby.
This generally lowers potential data loss and can also improve fail over times.
Oh, and while you're busy reading the docs... check out the Data Guard Broker
if you haven't already...
On Wed, Jul 30, 2014 at 9:35 PM, Michael Cunningham <napacunningham@xxxxxxxxx>
wrote:
Are there dangers with not having standby redo logs in a 12c physical standby
db? The docs do indicate they are necessary to insure zero data loss. Any other
experience out there?
Thanks,
Michael Cunningham
--
Nassyam Basha.
Oracle DBA
<http://www.pythian.com/> The Pythian Group
11g OCP Certified, Blogger
Co-Author: Oracle Data Guard 11gR2
<http://www.amazon.in/Oracle-Guard-11gR2-Administration-Beginners/dp/1849687900>
Member of Oraworld-team <http://www.oraworld-team.com>
<http://www.oraclefromguatemala.com.gt/wp-content/uploads/2014/03/oraworld.png>
Visit My Blog <http://www.oracle-ckpt.com>
Let's Connect - Linkedin Profile <http://in.linkedin.com/in/nassyambasha/>
My Twitter <https://twitter.com/nassyambasha>
My Facebook <https://www.facebook.com/nassyambasha>
Other related posts:
