Oracle 10gR2 Data guard physical or logical standby server?

Hi
We are planing to implement an Oracle 10gR2 data guard standby server for DR purposes, I found out that there are two type of standby server which is logical and physical standby server. I want to know which one is preferable? in term of complexity of setup and maintenance?
regards

Well it depends on what you mean by maintenance. I found the physical standby to be very little trouble at all ; however the logical standby has restrictions on it that the physical standby does not. In essence the physical standby merely digest archive logs; where as the logical standby uses logminer like functionality to process sql statements much like Oracle streams.
Hope that helps,
-JR jr.

Similar Messages

Goldengate from physical standby with Active data guard or from logical standby - which is better?

Hi,
We have Oracle 11.2.0.4 and are currently using Active Data Guard on a physical standby. My boss wants me to use Goldengate
to replicate several schema from Oracle to SqlSserver. She doesn't want to touch the Primary, which is in production. Would it be better
to setup a Logical standby for Goldendate to use, in addition to the Physical standby? Or will it be sufficient to use the Physical standby?
The application tables don't all have primary keys. I'm trying to decide if the Logical standby adds another layer of complexity or would
introduce delays in getting the data from Oracle to Sqlserver.
Thanks in advance,

Hi,
In this case I recommend you to use physical standby + Golden gate with ALO mode. You might have sligthly more trouble in logical standby. it means you might have more trouble at Goldengate's extract side.
You said
The application tables don't all have primary keys.
so you have to add keycols on replicat side.
I recommend you to add an index which should consist of keycols columns. it will be necessary for replicat performance.
Best Regards

Oracle Data Guard: Physical and Logical

I have a Primary database and have created a Physical Standby on another node. The physical standby is kept in synch via REDO Aply - online redo logs.
QUESTION: is it possible to create a Logical Standby off of the Physical Standby? I dont think so since the logical is kept in synch from a primary via SQL- Aply. CAN SOMEONE PLEASE CONFIRM.
I thought that a logical standby MUST be created from a Primary and not a Physical.
Thanks!!

Documentation is your friend,Orace does not not hide the information,how to create a logical standby:
http://download.oracle.com/docs/cd/E11882_01/server.112/e10700/create_ls.htm#g105412
Werner

Data Guard Physical Standby Failover

I need clarification on Physical Standby Failovers. Say I have a Primary db (A) and a physical standby (B), (A) fails and (B) is now the primary, can (A) be setup to become a standby of (B)? I've read 2 different statements in Oracle 10g Data Guard Concepts and Admin
"During failovers involving a physical standby database: In all cases, after a failover, the original primary database can no longer participate in the Data Guard configuration."
vice
"After a fast-start failover occurs, the old primary database will automatically reconfigure itself as a new standby database upon reconnection to the configuration."
Much thanks.

In all cases, after a failover, the original primary database can no longer participate in the Data Guard configuration.
TRUE ! But this doesn't mean that you cannot make your failed primary a new standby database !.
You can achieve this using FLASHBACK DATABASE option:
From the documentation:
After a failover occurs, the original primary database can no longer participate in the Data Guard configuration until it is repaired and established as a standby database in the new configuration. To do this, you can use the Flashback Database feature to recover the failed primary database to a point in time before the failover occurred, and then convert it into a physical or logical standby database in the new configuration.
Read the following documents:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/role_management.htm#sthref995
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/scenarios.htm#i1049997
In addition to this I'd like to mention that you can achieve the same with doing an incomplete recovery instead of using FLASHBACK DATABASE.
"After a fast-start failover occurs, the old primary database will automatically reconfigure itself as a new standby database upon reconnection to the configuration."
TRUE. If you enable Fast-Start Failover:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/sofo.htm#CHDDFFEC
Cheers!

About Data Guard - Physical Standby Database

Dear All,
I have read many documents regading Data Guard.
I am about to setup Data Guard in our current environment but want to clear few tings.
I have a confusion between physical and logical standby database.
What I have read from different documents is:
-Physical Standby Database in (11g)
1) It is the most efFicient
2) I can be either in mount or open state
3) Select queries and reporting can be done to improve performance of the primary database.
4) Schema on primary and standby database is always the same
-- Logical Standby Database
1) You can create additional tables, indexes, etc.
2) Always in open mode
3) Select queries and reporting can be done to improve performance of the primary database
Now our scenerio is, that we have one server at the moment, OS is linux and operating system is 11g. We want to setup an other server in another country, will also be 11g on Linux in a way that it acts as standby/backup server. Schema and data is always the same. In case due to unavailability of primary server, standby server acts as the primary server (This has to be automated). The reason for unavailability could be any like maintenance work on primary server, network or hardware failure at primary server. The last and the most important thing is that users from this country where we will setup standby database will insert/update data on the primary server BUT queries and reporting will be done from this newly created standby data.
Kindly recomend the best Data Guard in this scenerio and kindly correct me where I am wrong.
Thanks, Imran

A logical standby has various limitations on things like data types. It's also a much more complex architecture, which makes it more likely that something will break periodically and require attention. Applying redo to a physical standby is code that has been around forever and is as close to bullet-proof as you'll get. And you would generally prefer to fail over to a physical standby-- if you do things like create new objects in the logical standby, you may have to get rid of those objects during a failover to get acceptable OLTP performance.
Justin

What is the role of Lns process in oracle 10g data guard

Hi ,
plz help me out to find out the actual working of lns process in oracle 10g data guard
when i use SYNC redo transport
the output of v$managed_stanbdy is like that ..
PROCESS PID STATUS CLIENT_PROCESS GR# SEQ#
ARCH 9258 CLOSING ARCH 2 498
ARCH 9260 CLOSING ARCH 1 499
ARCH 9262 CLOSING ARCH 2 496
ARCH 9264 CLOSING ARCH 1 497
LGWR 9206 CLOSING LGWR 2 482
its not display any info about lns,thats means lns is not working in SYNC redo transport mode ?
but if i changed it to ASYNC then the out put of v$managed_stanbdy is like this ..
PS PID STS CPS GR# SEQ#
ARCH 9258 CLOSING ARCH 1 509
ARCH 9260 CLOSING ARCH 2 510
ARCH 9262 CLOSING ARCH 1 505
ARCH 9264 CLOSING ARCH 2 508
LGWR 9206 CLOSING LGWR 1 503
LNS 10528 CLOSING LNS 2 510
Now it display all the info about lns process...
i read in oracle documentation that lns process send redo data from primary,( through network service ) to RFS on standby side.
but first output means that lns is not working,if not then which process send redo from primary to RFS on standby ?
i also read in some blog that lgwr use some extra buffer size from primary db SGA ,to write redo in that buffer ,ans lns read redo from that buffer and send it to RFS on stanby side,
i m totally confused ..can u plz help me with correct logic behind this .
thanx in advance.

Hello,
On the primary database when you run the v$managed_standby, it shows up the LNS process as this process sends redo info to the standby database and on the standby database the RFS process receives the redo information.
So on the primary database when you query the v$managed_standby, it shows up LNS and on the standby database when you query the v$managed_standby it shows up RFS. Please let us know where you are running the query.
Refer this http://datadisk.co.uk/html_docs/oracle_dg/architecture.htm
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Total Posts:     9
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Name     Hemendra Singh
Location     NoidaPlease consider closing your questions by providing appropriate points and marking it as answered. Please keep the forum clean !

Streams Replication:Source database Physical or Logical Standby DB

Can the source database in streams replication be a physical or logical standby database ? If so, is the process of configuring streams the same as a regular database ? Are there any best practices or different configuration if the source is Logical or Physical standby DB ?
Thanks in advance.

Never done it, but I don't see any reason why it should not work.
Streams, at capture site, is only a data dictionary game and in a logical standby your data dictionary is open read write.
Streams, at capture site, never touch the source tables, in fact they may even not exists from Streams point of view,
as it deals only with the redo that are generated.
So Streams horizon is limited to the data dictionary, the log buffer, the archives and, in SYSAUX tablespace, all the LOGMNR_% tables. All these structures are read write in the logical standby. However, for the capture/propagation you may have to set to true the 'include_tagged_lcr' parameters.

Oracle 9i Data Guard - what language?

Is Oracle 9i Data Guard written in Java or some other language?
Thanks in advance-
Cathy

YES, we are currently using Data guard on 2000 Windows Server. Will need to have the Management server installed in order to get the Data guard function.

Oracle 9i Data Guard supported on Windows 2000 platform ?

Is Oracle 9i Data Guard supported on Windows 2000 platform ?

YES, we are currently using Data guard on 2000 Windows Server. Will need to have the Management server installed in order to get the Data guard function.

Difference between physical and logical standby database

What is the difference between physical and logical standby database?

Hi,
Physical Standy where its a read only DB.
Logs are applied.
Logical Standy where it can be Read / Write DB and the logs are applied in terms of SQL Statements.
Thanks & Regards,
Pavan Kumar N

Oracle 9i Data Guard Manager

Hi experts,
Does Oracle 9i Data Guard Manager software comes with oracle Enterprise edition.
Please tell from where to get this software
Thanks

hi,
Yes it does. You can access it from the command line with the utility dgmgrl.
rgds
alan

Oracle 9i Data Guard Documentation

Hi,
I am trying to get documentation on Oracle 9i Data Guard.
When I am at this url: http://www.oracle.com/technology/deploy/availability/htdocs/DataGuardOverview.html
I then activate the link on the right for "Oracle 9i Data Guard Documentation".
However, the link moves me to "Oracle 9i list of books", instead of where I want to be.
Can you please rectify this or send me the link to get this documentation.
Thanks,
Jason Metzker

Hi
The response I received in regards to the links to the Oracle 9i Data Guard Documentation page is that the link is correct.
The Data Guard doc is part of the database documentation set which is why the Oracle 9i Data Guard Documentation links takes you to the list of books. The Data Guard Documentation is also listed in the list of books.
Thanks & Regards,
Chao

Why FRA filling faster in logical standby server.

I have two standby servers one physical and one logical for my primary database. I have notice that on logical standby server the FRA is filling faster then physical standby server. Any one have some suggestions.
Thx

>
I have two standby servers one physical and one logical for my primary database. I have notice that on logical standby server the FRA is filling faster then physical standby server. Any one have some suggestions.
>
That is to be expected, because the logical standby not only creates archive logs on behalf of the transmission from the primary but also generates its own archivelogs on behalf of the filling (& archiving) of the local online logfiles. If you watch a logical standby applying, you may notice that the standby logs are getting archived and the online logs as well. That is significant for a logical standby and leads to (at least temporary) higher space consumption in the recovery area. Temporary, because the applied archive logs can get deleted (automatically, if you allow that).
Kind regards
Uwe
http://uhesse.wordpress.com

Shutdown Logical Standby Server

How can I gracfully shutdown logical standby server and start it ? Please write the steps
Thanks

Hello,
$> sqlplus '/as sysdba'
$> shutdown immediate ;
or
$> shutdown;
$> startup force nomount
or
$> startup force nomount pfile='..../yourinitstandby.ora'
$> alter database mount standby database.Verify in alert.log file that standyby server started and mounted.
Regards

Read-only agent synching to a Data Guard physical standby?

Hi all,
we are trying to use TimesTen 11.2.2.4.1 as a read-only memory cache for an Oracle 11.2.3.0.7 schema on Linus RedHat 6.3, while using Oracle Data Guard to replicate the Oracle instance over geographically remote sites. On each site we would like to have two TT instances synchronizing with the local Oracle 11g instance. This works fine against the master DB, but are the TT agents going to be able to synchronize against physical standby instances?
The problem it seems is that the TT agent uses dedicated structures in the Oracle master instance (related to the cache grid), which are going to be replicated into the standby instances. Is the TT agent able to use the read-only, replicated structures to complete synchronization, or is this approach unworkable? What would be your advise as how to achieve this?
Thanks for your help,
Chris

Hi again,
so after testing a little bit it appears that this approach works indeed, at least against a limited number of manual DML operations. What I needed to do on the slave instance to have it working is the following:
1 - Entirely exclude TTADMIN and TIMESTEN schemas from the Data Guard replication:
ALTER DATABASE STOP LOGICAL STANDBY APPLY;
execute dbms_logstdby.skip(stmt => 'SCHEMA_DDL', schema_name => 'TTADMIN', object_name => '%');
execute dbms_logstdby.skip(stmt => 'SCHEMA_DDL', schema_name => 'TIMESTEN', object_name => '%');
execute dbms_logstdby.skip(stmt => 'DML', schema_name => 'TTADMIN', object_name => '%');
execute dbms_logstdby.skip(stmt => 'DML', schema_name => 'TIMESTEN', object_name => '%');
ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE;
2 - Erase both schemas from the local instance:
DROP USER TTADMIN CASCADE;
DROP USER TIMESTEN CASCADE;
CREATE USER TTADMIN etc
3 - Temporarily disable the database guard while creating the local ttCache structures, as the scripts seem to need to set a table-level lock on the source table:
ALTER DATABASE GUARD NONE;
ttIsql> CREATE READONLY CACHE GROUP etc
ALTER DATABASE GUARD STANDBY;
4 - Unset the "Fire_Once_Only" property for the local TTADMIN triggers:
execute dbms_ddl.set_trigger_firing_property(trig_owner=> 'TTADMIN', trig_name=> 'TT_06_70560_T', fire_once => FALSE);
At that point the cache seems to replicate properly in the most simple cases. I will try to test with some substantial load and against DG failovers to see how this behaves.
Regards,
Chris

Oracle 10gR2 Data guard physical or logical standby server?

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