DR for a logical standby

Friends,
Oracle version 10.2.0.4:
On the primary site, we have one non-rac primary database P1. We will create a logical standby (L1) on primary site to be used for reporting. This logical standby L1 will have its own additional indexes and materialized views.
On the Disaster recovery site, which is at a remote location, a physical standby P2 will protect the primary database P1. What should be done such that the logical database L2 on the disaster recovery site remains in sync with L1? Also, if we were to lose the primary site, what should be done such that L2 gets fed by P2 after P2 takes over as primary?
Is such a configuration possible?
thanks for any thoughts.

Hi,
If you setup a physical standby L2, which will be sync with L1 this will be a cascaded configuration.
P1 --> L1 (logical) --> L2 (physical)
But this configuration is not supported. (It used to be, but not now... ) From my blog post about cascade standby databases: (http://emrebaransel.blogspot.com/2010/08/dataguard-cascade-standby-database.html)
The Layer1 standby database cannot be a logical standby where Layer2 can be. (Oracle mentions about Layer1 logical standby configuration on 10gR2 doc, and indicates that a Layer1 logical standby will generate and transmit redo information which won’t be identical with the one between primary and Layer1 standby. As a result "Layer2 physical standby databases created from a logical standby database will be a block-for-block copy of the logical standby database and a logical copy of the original primary database.”
But it is indicated that information in Metalink bulletin 409013.1 replaces Appendix E Cascaded Destinations, of Oracle Data Guard Concepts and Administration 10g Release 2 document. Metalink bulletin 409013.1 and 11gR1 doc says that “A logical standby database cannot forward redo to another standby database” and specifies that Layer1 logical standby configuration is not supported.
A logical standby database cannot forward redo to another standby database
At the end, this means you're not able to keep a copy of L1 logical standby.
But you can have this:
P1 --> P2 (physical) --> L2 (logical)
L2 will be sync with primary (P1). In a case of disaster it will still be sync with new primary (P2). But you need to maintain its own additional indexes and materialized views.

Similar Messages

Best Way to setup a disaster Recovery site for a logical standby database

I have a logical standby DB (L1DB) as a reporting db on the same machine as the primary (P1DB). We are planning on building a disaster recovery site with similar hardware and potentially have disk mirroring of atleast the redo log files.
The DR site can hold an additional physical standby (S1DB) for the primary (P1DB). I am trying to understand what would be the best way to setup the Disaster Recovery site for the L1DB logical stdby. Ideally, when the disaster happens, and I no longer have P1DB and L1DB, I should be able to switch to S1DB as the new primary. But how do I setup to have a L2DB that takes the place of L1DB and has its contents and can be setup as a logical standby of S1DB?

If you already setup one logical standby, then you know how it works, so not sure what question you are asking ?
Personally I would setup L2DB as a standby of the original primary P1DB. Having downstream standby databases complicates things, and adds additional lag between primary transaction time and L2DB apply.

Oracle9i Data Guard - Filtering for a Logical Standby DB?

Hello All
1) When using Oracle9i data guard with a logical standby database is it possible to "screen" the sql statements that are executed? For example if I don't want any "delete" commands to be replicated on the standby box can I filter them out?.
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Thanks in advance
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can I rename datafiles Yes. The database file names can be changed.
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You'd still have to setup DataGuard ! (and I wonder if you'd have complications setting up Active DataGuard).
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Logical standby and Primary keys

Hi All,
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I have not event put my main DB in force logging mode. This is because, redo log files or standby redo logfiles transforms into set of sql statements to update logical standby.
Have you done any DML operations with nologging options and do you notice any errors in the alert.log? I just curious to know.
But I wanted to know that, while system tablespace in hot backup mode,In the absence of both a primary key and a nonnull unique constraint/index, all columns of bounded size are logged as part of the UPDATE statement to identify the modified row. In other words, all columns except those with the following types are logged: LONG, LOB, LONG RAW, object type, and collections.
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Logical Standby Creation Problems "Create STatus Unknown"

We are using Grid Control 10.2.0.3 on Oracle 10.2..0.3 databases, Windows 2003 sp2 machines.
We have a primary and fsfo physical standby working properly. We went to create a logical standby on a separate server and had problems. it turned out that the listener on the server was not discovered on the target. we fixed that problem and finished the creation of the logical standby and it seems to be functioning properly now.
However, the status on the data guard page for the logical standby shows Create Status Unknown and we are unable to proceed on to create an additional standby database for other purposes. We have tried removing the logical standby target and re-discovering it but status still shows Create Status Unknown.
Is there any way to clear this status without having to drop the logical standby and completely recreate it.

The status on the agent shows it uploading successfully.
We resolved the issue by removing the logical standby from the configuration and selecting to retain the log apply. We then re-added the standby selecting to manage an existing standby database and the status went to normal.

Procedure for creating logical standyby database for oracle 11g?

Hi all,
can anybody provide me docs /procedure for creating logical standby databse for oracle 11g standard edition.
Aravind

Aravind,
1. The Oracle Standard Edition does not have standby mechanism, you should do it manually or go for Enterprise Edition.
2. It's rather a question for General Database Discussions instead of Peoplesoft.
Any further question regarding that point, please post out there.
Nicolas.

Primary Archivelog Management When Using Logical Standby

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Regards
Tim

Even with 1 TB of space I only have room enough for about 3 days worth of archivelogs. Working in the environment that I do, there is another group in charge of the ESAN which serves many different systems. They were wanting detail reasoning and justification why I needed 3 days worth of space when I requested it.
It is not truly a problem, there are always work arounds. I can restore from the backups, I can put in scripts to send out email notification when the standby falls to far behind the OE. However even with all that, I wanted to write a script that someone could run without having to check the system to delete the archivelogs if space becomes an issue on the production side.
I was just hoping to see if anyone had a script to do it already.
Thanks for all the input.
Regards
Tim

Controlling "Log apply" on Logical standby.

Hi,
We are going Live with logical standby ina day or two, and suddenly found what seems to be a potential problem in the near future.
Despite issuing the command
ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE;Logs are not getting applied immediately. Each of the logfile is taking somewhere around 5 to 10 minutes. That, was considered not so serious a problem. But sometimes, we find that there are too many logfiles left behind, and it is taking more than a day to get applied. I don't know how to prevent such a situation. I don't know how to get them all applied if at all such situation arises.
DB Version: 10.2.0.4
O/S: RHEL 4
Logfile size: 50M
Please help. I will be prepared with all documents to face this situation.
Aswin.
Edited by: ice_cold_aswin on May 6, 2010 7:12 PM

In Logical Standby the redo generated on the primary is converted to SQL and applied at the Logical Standby DB.
Check the network to see if there is any latency. And also check the views like v$system_event to get an overview of the wait events on the Primary DB.
Once refer to the docs for the Logical Standby Wait events.
Edited by: user8710159 on May 6, 2010 10:15 AM

When using DataGuard, the logical standby DB is already "OPEN"?

When I was setting up the physical standby DB several years ago no DataGuard got involved), I had the impression that the standby DB is in MOUNT status.
But since when using DataGuard to set up the logical standby DB, the logical standby DB can be used as it is already OPENed.
Is it actually in OPEN status? If so, can the primary and logical standby have the same SID without any trouble?
Please help advise. Thanks a lot!

Hello Christy,
yes it is ok that both database are in status OPEN, that is also the main reason for using logical standby databases (you can do changes and queries on standby too).
I hope you don't use a logical standby database in a SAP environment, because of this is NOT supported. Check sapnote #105047 - Point "14. Data Guard". A logical standby database has limitations.
If you just want to use the physical standby database for queries you can open it in read only or you can use flashback technology for read/write. With Oracle 11g you have these features included in data guard itself (Active Data Guard / Snapshot StandBy) to perform such steps automatically.
Regards
Stefan

Oracle 10g Logical Standby

The question is on Oracle 10g Logical Standby Data Guard. Below is the short description of what we wanted to do.
We currently run our Remedy application on Oracle10g. We wanted to setup Data Guard (logical standby) so we can perform our application upgrade on the logical standby. While we upgrade our application, our customers perform the dml on the primary instance.
During the upgrade, we will change the ddl on our application in the logical standby instance. After the application upgrade, we do a role switch between the two instances (primary became a new logical standby and logical standby became new primary). Now, we wanted the data or the dml that our customers perform on the old primary replicate over to the new primary.
It is possible for the logical standby to perform the ddl at the same time user perform the ddl and dml on the primary instance?
After role switch between the two instances, is the data changed on the primary replicate over to the new primary?
Thank you for your helps.
Loc Nguyen
[email protected]

Hi Shital,
Guard_status protects the data from being changed.
ALL- By default it is not possible for a non-privileged user to modify data on a data guard SQL apply database. This is because the database guard is automatically set to ALL.
With this level of security, only SYS user can modify the data.
STANDBY- When you set this level of security, users are able to modify data that is not maintained by the Logical apply engine.
NONE permits any users to access the standby database as long as they have correct privileges. This is the normal security for all data in the database.
You can change the guard status value from ALL to NONE in order to allow non-privileged users to modify data and Yes you can create user and extra tablespace in logical standby database..this is what the one of advantage of using Logical standby database.
SQL> ALTER DATABASE GUARD NONE;
Thanks

Physical standby and logical standby

Hi,
Why we mention standby_archive_dest and log_archive_Dest in standby init.ora.
bcz there is no activity at physical standby.so why we set two parameters?
what is difference between physical stand by and logical standby?

Hi,
A logical standby database contains the same logical information as the production database, although the physical organization and structure of the data can be different. The SQL apply technology keeps the logical standby database synchronized with the primary database by transforming redo data received from the primary database into SQL statements and then executing the SQL statements on the standby database. This makes it possible for the logical standby database to be open read-write and accessed for queries and reporting purposes at the same time the SQL is being applied to it.
Logical vs Physical Standby database
http://www.orafaq.com/node/957
Regards,
Tom
Edited by: Soli on 19.8.2009 13:48

Determining the last archive applied on Logical Standby

Hi,
I am trying to determine the last log received and applied on my Logical Standby
SQL> select thread#, max(sequence#) "Last Standby Seq Received"
from v$archived_log val, v$database vdb
where val.resetlogs_change# = vdb.resetlogs_change#
group by thread# order by 1;
THREAD# Last Standby Seq Received
1 14
SQL> select thread#, max(sequence#) "Last Standby Seq Applied"
from v$archived_log val, v$database vdb
where val.resetlogs_change# = vdb.resetlogs_change#
and applied='YES'
group by thread# order by 1;
Does not return anything
These statements work ok on a physical standby.
I know Sql Apply is enabled on my logical standby - my broker configuration is enabled and for the logical standby database, it is showing the Intended State as APPLY-ON with no Transport or Apply Lag on any of the databases
Q. How do I determine the last seq applied on my logical standby ?
thanks,
Jim

Hello;
I have this from my notes:
SELECT
L.SEQUENCE#,
L.FIRST_TIME,
(CASE WHEN L.NEXT_CHANGE# < P.READ_SCN THEN 'YES'WHEN L.FIRST_CHANGE# < P.APPLIED_SCN THEN 'CURRENT' ELSE 'NO' END) APPLIED
FROM
DBA_LOGSTDBY_LOG L, DBA_LOGSTDBY_PROGRESS P
ORDER BY SEQUENCE#;
Best Regards
mseberg

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

Real time apply for logical standby

Hi
Oracle 11.2.0.3.0
I have a primary database orcl and logical standby database orcl_std.
Real time apply is enabled. I have standby redologs in both primary and standby sides and I`ve started recovery with below command:
ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE;
When I create a new table in primary database, I am unable to see it on standby database (Although real time apply is enabled)
However, when I switch log in primary, I can see the new table in standby database.
My question is, why realtime apply is not working in my scenerio ? I was expecting to see the new table immediately in standby database once it is created in primary database. Why am I supposed to wait for log switch in real time apply ?

Using Real-Time Apply to Apply Redo Data Immediately
http://docs.oracle.com/cd/E11882_01/server.112/e25608/log_apply.htm#i1022881
1.What is compatible parameter, it should be 11.1
2.Try to check parameters mentioned in below link:
http://easyoradba.com/2011/01/10/real-time-apply-in-oracle-data-guard-10g/
Regards
Girish Sharma
Edited by: Girish Sharma on Nov 15, 2012 12:37 PM

Logical Standby: WAITING FOR DICTIONARY LOGS status.

Hi,
I have just configured a Logical Standby from Physical Standby, I followed all steps explained in section 4.2.1 from the Oracle® Data Guard Concepts and Administration 10g Release 2 (10.2) documentation, but now my logical standby stay on WAITING FOR DICTIONARY LOGS more than 3 days, all archives from primary DB have been replicated and registered, I don't understand whats
wrong.
SQL> SELECT * FROM V$LOGSTDBY_STATE;
PRIMARY_DBID SESSION_ID
REALTIME_APPLY
STATE
144528764 1
Y
WAITING FOR DICTIONARY LOGS
Fri Apr 8 18:05:47 2011
RFS LogMiner: Registered logfile [/archive/dbp/581440892_1_0000157573.arc] to LogMiner session id [1]
Fri Apr 8 18:10:55 2011
RFS LogMiner: Client enabled and ready for notification
Fri Apr 8 18:10:55 2011
Primary database is in MAXIMUM PERFORMANCE mode
RFS[3]: Successfully opened standby log 4: '/redo2a/dbp/redo4a_stb.log'
Fri Apr 8 18:10:58 2011
RFS LogMiner: Registered logfile [/archive/dbp/581440892_1_0000157574.arc] to LogMiner session id [1]
Fri Apr 8 18:15:54 2011
RFS LogMiner: Client enabled and ready for notification
Fri Apr 8 18:15:54 2011
Primary database is in MAXIMUM PERFORMANCE mode
RFS[3]: Successfully opened standby log 3: '/redo1a/dbp/redo3a_stb.log'
Fri Apr 8 18:15:57 2011
RFS LogMiner: Registered logfile [/archive/dbp/581440892_1_0000157575.arc] to LogMiner session id [1]Thanks in advance.
My Oracle version is: 10.2.0.4
My Platform is: AIX 6.1
Nataly.

On standby alert no error messages found.
RFS LogMiner: Client enabled and ready for notification
Mon Apr 11 18:09:58 2011
Primary database is in MAXIMUM PERFORMANCE mode
RFS[3]: Successfully opened standby log 4: '/redo2a/mefsf/redo4a_stb.log'
Mon Apr 11 18:10:01 2011
RFS LogMiner: Registered logfile [/archive/mefsf/581440892_1_0000157782.arc] to LogMiner session id [1]
Mon Apr 11 18:23:16 2011
RFS LogMiner: Client enabled and ready for notification
Mon Apr 11 18:23:16 2011
Primary database is in MAXIMUM PERFORMANCE mode
RFS[3]: Successfully opened standby log 3: '/redo1a/mefsf/redo3a_stb.log'
Mon Apr 11 18:23:18 2011
RFS LogMiner: Registered logfile [/archive/mefsf/581440892_1_0000157783.arc] to LogMiner session id [1]Continues
On primary alertlog,
There is a common message:
ORACLE Instance bdprod - Archival Error. Archiver continuing.
Mon Apr 11 18:22:57 2011
Errors in file /oracle/app/oracle/admin/bdprod/bdump/bdprod_arc4_2818414.trc:
ORA-00308: cannot open archived log '/archive/bdprod/581440892_1_0000157545.arc'
ORA-27037: unable to obtain file status
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3
Mon Apr 11 18:22:57 2011
FAL[server, ARC4]: FAL archive failed, see trace file.
Mon Apr 11 18:22:57 2011
Errors in file /oracle/app/oracle/admin/bdprod/bdump/bdprod_arc4_2818414.trc:
ORA-16055: FAL request rejected
ARCH: FAL archive failed. Archiver continuing
Mon Apr 11 18:22:57 2011
ORACLE Instance bdprod - Archival Error. Archiver continuing.
Mon Apr 11 18:22:57 2011
Errors in file /oracle/app/oracle/admin/bdprod/bdump/bdprod_arc1_7078038.trc:
ORA-00308: cannot open archived log '/archive/bdprod/581440892_1_0000157546.arc'
ORA-27037: unable to obtain file status
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3
Mon Apr 11 18:22:57 2011
FAL[server, ARC1]: FAL archive failed, see trace file.
Mon Apr 11 18:22:57 2011
Errors in file /oracle/app/oracle/admin/bdprod/bdump/bdprod_arc1_7078038.trc:
ORA-16055: FAL request rejected
ARCH: FAL archive failed. Archiver continuing
Mon Apr 11 18:22:57 2011
ORACLE Instance bdprod - Archival Error. Archiver continuing.

DR for a logical standby

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