Beiträge getaggt mit Snapshot Standby
After Test-Failover, make NEW Primary Standby again
Maybe we want to test Failover, although the Primary is working fine. After the failover succeeded, we have an OLD Primary then and a NEW Primary. There is a well documented way to convert the OLD Primary into a Standby. This procedure is called Reinstate. This posting shows how to make the NEW Primary a Standby again. The OLD Primary will keep on running as Primary – with all productive users connected there still. A special case why we may want to do that is because we tested Failover to a Snapshot Standby that has no network connection to the Primary.
The initial configuration:
DGMGRL> show configuration Configuration - myconf Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS
The version is still 11.2.0.1 like in the previous posting. I will now failover to physt while prima keeps running. Attention: If there is a productive service started on the NEW Primary, make sure to stop it. Else new productive connections will access the NEW Primary! We will deliberately cause a Split Brain situation here with two Primary Databases. This may cause problems in a productive environment and is not recommended.
DGMGRL> failover to physt; Performing failover NOW, please wait... Error: ORA-16600: not connected to target standby database for failover Failed. Unable to failover DGMGRL> exit [oracle@uhesse ~]$ dgmgrl sys/oracle@physt DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> failover to physt; Performing failover NOW, please wait... Failover succeeded, new primary is "physt"
The error above shows that we cannot failover, connected to the (still working) Primary but must connect to the Standby first. Now there are two Primary Databases:
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdba SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:25:51 2012 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> select database_role from v$database; DATABASE_ROLE ---------------- PRIMARY SQL> connect sys/oracle@prima as sysdba Connected. SQL> select database_role from v$database; DATABASE_ROLE ---------------- PRIMARY
I want to make the NEW Primary a Standby again. Similar to a Reinstate, that needs Flashback Logs. My two Databases generate Flashback Logs, so that requirement is met.
SQL> connect sys/oracle@physt as sysdba
Connected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 313159680 bytes
Fixed Size 2212936 bytes
Variable Size 264244152 bytes
Database Buffers 41943040 bytes
Redo Buffers 4759552 bytes
Database mounted.
SQL> flashback database to before resetlogs;
Flashback complete.
SQL> alter database convert to physical standby;
Database altered.
This modified the controlfile and puts the Instance in NOMOUNT. We need to restart into MOUNT:
SQL> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 313159680 bytes
Fixed Size 2212936 bytes
Variable Size 264244152 bytes
Database Buffers 41943040 bytes
Redo Buffers 4759552 bytes
Database mounted.
SQL> recover managed standby database using current logfile disconnect;
Media recovery complete.
SQL> select status,sequence# from v$managed_standby where process='MRP0';
STATUS SEQUENCE#
------------ ----------
WAIT_FOR_LOG 12
We want to see here APPLYING LOG – the redo is not yet transmitted from the OLD Primary.
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> select sequence# from v$log where status='CURRENT';
SEQUENCE#
----------
13
SQL> alter system set log_archive_dest_2='service=physt db_unique_name=physt';
System altered.
SQL> alter system set log_archive_dest_state_2=enable;
System altered.
SQL> alter system switch logfile;
System altered.
SQL> connect sys/oracle@physt as sysdba
Connected.
SQL> select status,sequence# from v$managed_standby where process='MRP0';
STATUS SEQUENCE#
------------ ----------
APPLYING_LOG 15
Everything is fine now on the Database Layer: OLD Primary is still Primary, NEW Primary is again Standby, applying Redo from the OLD Primary. Only the Data Guard Broker is confused now – we need to create a new configuration:
[oracle@uhesse ~]$ dgmgrl sys/oracle@prima
DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production
Copyright (c) 2000, 2009, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Connected.
DGMGRL> show configuration;
ORA-16795: the standby database needs to be re-created
Configuration details cannot be determined by DGMGRL
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:46:13 2012
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> alter system set dg_broker_start=false;
System altered.
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> alter system set dg_broker_start=false;
System altered.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@uhesse ~]$ rm $ORACLE_HOME/dbs/dr*
The above deleted the Broker Config Files. Now we create a new Broker Configuration:
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdba SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:48:22 2012 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> alter system set dg_broker_start=true; System altered. SQL> connect sys/oracle@prima as sysdba Connected. SQL> alter system set dg_broker_start=true; System altered. [oracle@uhesse ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> create configuration mycon as primary database is prima connect identifier is prima; Configuration "mycon" created with primary database "prima" DGMGRL> add database physt as connect identifier is physt maintained as physical; Database "physt" added DGMGRL> enable configuration; Enabled. DGMGRL> show configuration; Configuration - mycon Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS
That was it 🙂
Failover to Snapshot Standby
In a recent Data Guard course that I tought, the question came up whether it is possible to failover to a Snapshot Standby if the Primary is lost. My answer was that this is of course possible but will take a longer time, because first the Snapshot Standby need to be converted back to Physical Standby and then all the collected Redo Protocol on the Standby site needs to be applied.
However, when we tried to do it, the Broker refused to do the convert and the failover, complaining about the Primary not being reachable. We needed to do the convert without the Broker then. Today, when I wanted to reproduce the issue, it worked like a charm, though:
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
This is the same version we had in the classroom. Now the configuration:
DGMGRL> show configuration
Configuration - myconf
Protection Mode: MaxPerformance
Databases:
prima - Primary database
physt - Snapshot standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
I will now shutdown the Primary like there is an emergency on the Primary Site:
[oracle@uhesse ~]$ sqlplus sys/oracle@prima as sysdba SQL*Plus: Release 11.2.0.1.0 Production on Sat Jan 14 09:42:47 2012 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> shutdown abort ORACLE instance shut down.
Now with the Broker, a convert fails:
[oracle@uhesse ~]$ dgmgrl sys/oracle@physt DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> convert database physt to physical standby; Converting database "physt" to a Physical Standby database, please wait... Error: ORA-01034: ORACLE not available Error: ORA-16625: cannot reach database "prima" Failed. Failed to convert database "physt"
That was until this point the same as in the class. But now my failover succeeds, while it did not in the class:
DGMGRL> failover to physt; Converting database "physt" to a Physical Standby database, please wait... Operation requires shutdown of instance "physt" on database "physt" Shutting down instance "physt"... Database closed. Database dismounted. ORACLE instance shut down. Operation requires startup of instance "physt" on database "physt" Starting instance "physt"... ORACLE instance started. Database mounted. Continuing to convert database "physt" ... Operation requires shutdown of instance "physt" on database "physt" Shutting down instance "physt"... ORA-01109: database not open Database dismounted. ORACLE instance shut down. Operation requires startup of instance "physt" on database "physt" Starting instance "physt"... ORACLE instance started. Database mounted. Database "physt" converted successfully Performing failover NOW, please wait... Failover succeeded, new primary is "physt"
All is fine now. It worked as it was supposed to. But it was a little scary, though, that it wasn’t possible to do the very same in the class – not sure what was different there. My advice based upon this experience would be to test the failover to a Snapshot Standby that has no connection to the Primary. Also, consider to configure two Standby Databases and use only one as Snapshot Standby. And notice the manual convert in case:
SQL> alter database convert to physical standby;
Clone Database from Snapshot Standby Database
In 11g, we introduced the new feature Snapshot Standby Database for Data Guard. In my current Data Guard course, one of the attendees asked, whether it is possible to create a Database Clone out of such a Snapshot Standby Database. Maybe you want to preserve the changes that have been done during the time, your Physical Standby Database was turned into a READ-WRITE opened (Test-)Database. I answered that this is mot likely possible, but I did not try yet. Now I did 🙂
DGMGRL> convert database physt to snapshot standby; Converting database "physt" to a Snapshot Standby database, please wait... Database "physt" converted successfully
There is my Snapshot Standby Database. You may reproduce the Data Guard Configuration in place here with the Whitepaper 11g Data Guard on the Command Line from my Downloads page.
DGMGRL> show configuration
Configuration - myconf
Protection Mode: MaxPerformance
Databases:
prima - Primary database
physt - Snapshot standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
I continue to prepare a Clone Database by creating an spfile and a password file for it (very similar as described in the Whitepaper for the physt Database). Then I start it into NOMOUNT:
uhesse $ sqlplus sys/oracle@clon as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Tue Dec 21 17:00:26 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 313860096 bytes
Fixed Size 1336232 bytes
Variable Size 209718360 bytes
Database Buffers 96468992 bytes
Redo Buffers 6336512 bytes
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
The version in use is 11gR2, but it should work with 11gR1 the same way. Now RMAN is used to create the Clone from the Snapshot Standby:
RMAN> connect target sys/oracle@physt connected to target database: PRIMA (DBID=1970640575) RMAN> connect auxiliary sys/oracle@clon connected to auxiliary database: CLON (not mounted) RMAN> duplicate target database to clon from active database; Starting Duplicate Db at 21-DEC-10 using target database control file instead of recovery catalog allocated channel: ORA_AUX_DISK_1 channel ORA_AUX_DISK_1: SID=96 device type=DISK RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of Duplicate Db command at 12/21/2010 17:03:19 RMAN-05541: no archived logs found in target database RMAN> exit
Oops! I need Archivelogs on the Snapshot Standby. Note that they are in the same directory but with a different Resetlogs Identifier as the Archivelogs created when the Database was a Physical Standby Database.
uhesse $ sqlplus sys/oracle@physt as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Tue Dec 21 17:03:49 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> alter system switch logfile;
System altered.
SQL> select name from v$archived_log;
NAME
--------------------------------------------------------------------------------
/home/oracle/physt/archive/1_12_738347903.dbf
/home/oracle/physt/archive/1_8_738347903.dbf
/home/oracle/physt/archive/1_7_738347903.dbf
/home/oracle/physt/archive/1_9_738347903.dbf
/home/oracle/physt/archive/1_11_738347903.dbf
/home/oracle/physt/archive/1_10_738347903.dbf
/home/oracle/physt/archive/1_13_738347903.dbf
/home/oracle/physt/archive/1_14_738347903.dbf
/home/oracle/physt/archive/1_15_738347903.dbf
/home/oracle/physt/archive/1_1_738349098.dbf
10 rows selected.
Again we go with the duplicate:
RMAN> connect target sys/oracle@physt connected to target database: PRIMA (DBID=1970640575) RMAN> connect auxiliary sys/oracle@clon connected to auxiliary database: CLON (not mounted) RMAN> duplicate target database to clon from active database; Starting Duplicate Db at 21-DEC-10 using target database control file instead of recovery catalog allocated channel: ORA_AUX_DISK_1 channel ORA_AUX_DISK_1: SID=95 device type=DISK contents of Memory Script: { sql clone "alter system set db_name = ''PRIMA'' comment= ''Modified by RMAN duplicate'' scope=spfile"; sql clone "alter system set db_unique_name = ''CLON'' comment= ''Modified by RMAN duplicate'' scope=spfile"; shutdown clone immediate; startup clone force nomount backup as copy current controlfile auxiliary format '/home/oracle/clon/control01.ctl'; alter clone database mount; } executing Memory Script sql statement: alter system set db_name = ''PRIMA'' comment= ''Modified by RMAN duplicate'' scope=spfile sql statement: alter system set db_unique_name = ''CLON'' comment= ''Modified by RMAN duplicate'' scope=spfile Oracle instance shut down Oracle instance started Total System Global Area 313860096 bytes Fixed Size 1336232 bytes Variable Size 209718360 bytes Database Buffers 96468992 bytes Redo Buffers 6336512 bytes Starting backup at 21-DEC-10 allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=24 device type=DISK channel ORA_DISK_1: starting datafile copy copying current control file output file name=/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_physt.f tag=TAG20101221T172429 RECID=6 STAMP=738350670 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01 Finished backup at 21-DEC-10 database mounted contents of Memory Script: { set newname for datafile 1 to "/home/oracle/clon/system01.dbf"; set newname for datafile 2 to "/home/oracle/clon/sysaux01.dbf"; set newname for datafile 3 to "/home/oracle/clon/undotbs01.dbf"; set newname for datafile 4 to "/home/oracle/clon/users01.dbf"; backup as copy reuse datafile 1 auxiliary format "/home/oracle/clon/system01.dbf" datafile 2 auxiliary format "/home/oracle/clon/sysaux01.dbf" datafile 3 auxiliary format "/home/oracle/clon/undotbs01.dbf" datafile 4 auxiliary format "/home/oracle/clon/users01.dbf" ; sql 'alter system archive log current'; } executing Memory Script executing command: SET NEWNAME executing command: SET NEWNAME executing command: SET NEWNAME executing command: SET NEWNAME Starting backup at 21-DEC-10 using channel ORA_DISK_1 channel ORA_DISK_1: starting datafile copy input datafile file number=00001 name=/home/oracle/physt/system01.dbf output file name=/home/oracle/clon/system01.dbf tag=TAG20101221T172436 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:25 channel ORA_DISK_1: starting datafile copy input datafile file number=00002 name=/home/oracle/physt/sysaux01.dbf output file name=/home/oracle/clon/sysaux01.dbf tag=TAG20101221T172436 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:25 channel ORA_DISK_1: starting datafile copy input datafile file number=00003 name=/home/oracle/physt/undotbs01.dbf output file name=/home/oracle/clon/undotbs01.dbf tag=TAG20101221T172436 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:15 channel ORA_DISK_1: starting datafile copy input datafile file number=00004 name=/home/oracle/physt/users01.dbf output file name=/home/oracle/clon/users01.dbf tag=TAG20101221T172436 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03 Finished backup at 21-DEC-10 sql statement: alter system archive log current contents of Memory Script: { backup as copy reuse archivelog like "/home/oracle/physt/archive/1_3_738349098.dbf" auxiliary format "/home/oracle/clon/archive/1_3_738349098.dbf" ; catalog clone archivelog "/home/oracle/clon/archive/1_3_738349098.dbf"; switch clone datafile all; } executing Memory Script Starting backup at 21-DEC-10 using channel ORA_DISK_1 channel ORA_DISK_1: starting archived log copy input archived log thread=1 sequence=3 RECID=12 STAMP=738350751 output file name=/home/oracle/clon/archive/1_3_738349098.dbf RECID=0 STAMP=0 channel ORA_DISK_1: archived log copy complete, elapsed time: 00:00:15 Finished backup at 21-DEC-10 cataloged archived log archived log file name=/home/oracle/clon/archive/1_3_738349098.dbf RECID=12 STAMP=738350766 datafile 1 switched to datafile copy input datafile copy RECID=6 STAMP=738350766 file name=/home/oracle/clon/system01.dbf datafile 2 switched to datafile copy input datafile copy RECID=7 STAMP=738350767 file name=/home/oracle/clon/sysaux01.dbf datafile 3 switched to datafile copy input datafile copy RECID=8 STAMP=738350767 file name=/home/oracle/clon/undotbs01.dbf datafile 4 switched to datafile copy input datafile copy RECID=9 STAMP=738350767 file name=/home/oracle/clon/users01.dbf contents of Memory Script: { set until scn 226204; recover clone database delete archivelog ; } executing Memory Script executing command: SET until clause Starting recover at 21-DEC-10 allocated channel: ORA_AUX_DISK_1 channel ORA_AUX_DISK_1: SID=95 device type=DISK starting media recovery archived log for thread 1 with sequence 3 is already on disk as file /home/oracle/clon/archive/1_3_738349098.dbf archived log file name=/home/oracle/clon/archive/1_3_738349098.dbf thread=1 sequence=3 media recovery complete, elapsed time: 00:00:00 Finished recover at 21-DEC-10 contents of Memory Script: { shutdown clone immediate; startup clone nomount; sql clone "alter system set db_name = ''CLON'' comment= ''Reset to original value by RMAN'' scope=spfile"; sql clone "alter system reset db_unique_name scope=spfile"; shutdown clone immediate; startup clone nomount; } executing Memory Script database dismounted Oracle instance shut down connected to auxiliary database (not started) Oracle instance started Total System Global Area 313860096 bytes Fixed Size 1336232 bytes Variable Size 209718360 bytes Database Buffers 96468992 bytes Redo Buffers 6336512 bytes sql statement: alter system set db_name = ''CLON'' comment= ''Reset to original value by RMAN'' scope=spfile sql statement: alter system reset db_unique_name scope=spfile Oracle instance shut down connected to auxiliary database (not started) Oracle instance started Total System Global Area 313860096 bytes Fixed Size 1336232 bytes Variable Size 209718360 bytes Database Buffers 96468992 bytes Redo Buffers 6336512 bytes sql statement: CREATE CONTROLFILE REUSE SET DATABASE "CLON" RESETLOGS ARCHIVELOG MAXLOGFILES 26 MAXLOGMEMBERS 5 MAXDATAFILES 100 MAXINSTANCES 1 MAXLOGHISTORY 292 LOGFILE GROUP 1 ( '/home/oracle/clon/log_g1m1.rdo' ) SIZE 100 M REUSE, GROUP 2 ( '/home/oracle/clon/log_g2m1.rdo' ) SIZE 100 M REUSE DATAFILE '/home/oracle/clon/system01.dbf' CHARACTER SET WE8ISO8859P1 contents of Memory Script: { set newname for tempfile 1 to "/home/oracle/clon/temp01.dbt"; switch clone tempfile all; catalog clone datafilecopy "/home/oracle/clon/sysaux01.dbf", "/home/oracle/clon/undotbs01.dbf", "/home/oracle/clon/users01.dbf"; switch clone datafile all; } executing Memory Script executing command: SET NEWNAME renamed tempfile 1 to /home/oracle/clon/temp01.dbt in control file cataloged datafile copy datafile copy file name=/home/oracle/clon/sysaux01.dbf RECID=1 STAMP=738350787 cataloged datafile copy datafile copy file name=/home/oracle/clon/undotbs01.dbf RECID=2 STAMP=738350787 cataloged datafile copy datafile copy file name=/home/oracle/clon/users01.dbf RECID=3 STAMP=738350787 datafile 2 switched to datafile copy input datafile copy RECID=1 STAMP=738350787 file name=/home/oracle/clon/sysaux01.dbf datafile 3 switched to datafile copy input datafile copy RECID=2 STAMP=738350787 file name=/home/oracle/clon/undotbs01.dbf datafile 4 switched to datafile copy input datafile copy RECID=3 STAMP=738350787 file name=/home/oracle/clon/users01.dbf contents of Memory Script: { Alter clone database open resetlogs; } executing Memory Script database opened Finished Duplicate Db at 21-DEC-10
So this was pretty much the same as with an ordinary Clone from a Production Database – as expected. Now we turn the Snapshot Standby back into Physical Standby, thereby losing all the changes that might be done there by using Flashback Database internally. But the Clone Database will remain, now being an independent Database with another Name and DBID than the Primary resp. Snapshot Standby.
DGMGRL> convert database physt to physical standby;
Converting database "physt" to a Physical Standby database, please wait...
Operation requires shutdown of instance "physt" on database "physt"
Shutting down instance "physt"...
Database closed.
Database dismounted.
ORACLE instance shut down.
Operation requires startup of instance "physt" on database "physt"
Starting instance "physt"...
ORACLE instance started.
Database mounted.
Continuing to convert database "physt" ...
Operation requires shutdown of instance "physt" on database "physt"
Shutting down instance "physt"...
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
Operation requires startup of instance "physt" on database "physt"
Starting instance "physt"...
ORACLE instance started.
Database mounted.
Database "physt" converted successfully
DGMGRL> show configuration
Configuration - myconf
Protection Mode: MaxPerformance
Databases:
prima - Primary database
physt - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
SQL> connect sys/oracle@clon as sysdba
Connected.
SQL> select name,dbid,database_role from v$database;
NAME DBID DATABASE_ROLE
--------- ---------- ----------------
CLON 2202079427 PRIMARY
SQL> connect sys/oracle@physt as sysdba
Connected.
SQL> select name,dbid,database_role from v$database;
NAME DBID DATABASE_ROLE
--------- ---------- ----------------
PRIMA 1970640575 PHYSICAL STANDBY
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> select name,dbid,database_role from v$database;
NAME DBID DATABASE_ROLE
--------- ---------- ----------------
PRIMA 1970640575 PRIMARY
Conclusion: With 11g, we can very comfortably transform our Physical Standby into a fully changeable Snapshot Standby, clone that modified Database into an autonomous Database to keep the changes and afterwards transform the Snapshot Standby back into Physical Standby. During the whole action, Redo Protocol from the Primary Database can still be received – but not applied – on the Standby Site.