RE: Data Guard question
- From: "Sweetser, Joe" <JSweetser@xxxxxxxx>
- To: <John.Hallas@xxxxxxxxxxxxxxxxxx>
- Date: Mon, 13 Oct 2008 08:56:08 -0600
In a nutshell, I think the answer is yes. Note they are NOT a
requirement for all DG configurations, though.
-joe
From the DG Concepts & Administration manual:
2.5.2 Standby Redo Logs
A standby redo log is similar to an online redo log, except that a
standby redo log is used to store redo data received from another
database.
A standby redo log is required if you want to implement:
* The maximum protection and maximum availability levels of
data protection (described in Section 1.4 and in more detail in Section
5.6)
* Real-time apply (described in Section 6.2)
* Cascaded destinations (described in Appendix E)
A standby redo log provides a number of advantages:
* Standby redo log files can reside on raw devices, which may
be important if either or both the primary and standby databases reside
in a Real Application Clusters environment.
* Standby redo log files can be multiplexed using multiple
members, improving reliability over archived log files.
* During a failover, Data Guard can recover and apply more redo
data from standby redo log files than from the archived log files alone.
* The archiver (ARCn) process or the log writer (LGWR) process
on the primary database can transmit redo data directly to remote
standby redo log files, potentially eliminating the need to register a
partial archived log file (for example, to recover after a standby
database crashes). See Chapter 5 for more information.
-----Original Message-----
From: John.Hallas@xxxxxxxxxxxxxxxxxx
[mailto:John.Hallas@xxxxxxxxxxxxxxxxxx]
Sent: Monday, October 13, 2008 8:42 AM
To: Sweetser, Joe
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: Data Guard question
Why does that requirement for an additional srl exist? Is it so that the
target system can always keep up
John
-----<oracle-l-bounce@xxxxxxxxxxxxx> wrote: -----
To: Bradd Piontek <piontekdd@xxxxxxxxx>, <finn.oracledba@xxxxxxxxx>,
<jason.arneil@xxxxxxxxxx>
From: "Sweetser, Joe" <JSweetser@xxxxxxxx> Sent by:
<oracle-l-bounce@xxxxxxxxxxxxx>
Date: 13/10/2008 03:21PM
cc: oracle-l <oracle-l@xxxxxxxxxxxxx>
Subject: RE: Data Guard question
Not unexpectedly, it ended up be a combination of a few things:
1. Not enough standby redo logs - recommended value is one more than
the number of redo logs
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