Copyright (c) 2020, Oracle. All rights reserved. Oracle Confidential.

Handling ORL and SRL (Resize) on Primary and Physical Standby in Data Guard Environment (Doc ID 1532566.1)

In this Document
Goal
Solution
References

APPLIES TO:
Oracle Database - Enterprise Edition - Version 10.1.0.2 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
GOAL
NOTE: In the images and/or the document content below, the user information and environment data used represents fictitious data from the Oracle sample schema(s), Public Documentation delivered with an Oracle database product or other training material. Any similarity to actual environments, actual persons, living or dead, is purely coincidental and not intended in any manner.
For the purposes of this document, the following fictitious environment is used as an example to describe the procedure:

Primary Database: prm11203
Standby Database: std11203

It has been seen in cases where ORA-16401 and ORA-16055 reported in primary alert log when redo log switch is over frequently. So suggestion is to Increase the Size of the Online Redologs to reduce Redolog Switch Frequency. And this may also required to improve primary database performance.

So the purpose of this article is How to Increase size of Redo Logs in a Dataguard Environment when Physical Standby in place.

SOLUTION
Please note if using Maximum Protection mode, you need to downgrade to Maximum availability mode first and then perform the below steps. Starting with 11gR2 this no longer needs a Primary database restart to downgrade to Max Availability mode and then upgrade to Max Protection mode.

Primary Database:

$sqlplus sys/ as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Tue Feb 26 10:41:27 2013

Copyright (c) 1982, 2011, Oracle. All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select status,instance_name,database_role from v$database,v$instance;

STATUS INSTANCE_NAME DATABASE_ROLE

OPEN prm11203 PRIMARY

SQL> select group#,sum(bytes/1024/1024)"Size in MB" from v$log group by group#;

GROUP# Size in MB

     1         50
     2         50
     3         50

SQL> select group#,sum(bytes/1024/1024)"Size in MB" from v$standby_log group by group#;

GROUP# Size in MB

     6         50
     4         50
     5         50
     7         50

Standby Database:

$sqlplus sys/ as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Tue Feb 26 10:48:30 2013

Copyright (c) 1982, 2011, Oracle. All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select status,instance_name,database_role from v$database,v$Instance;

STATUS INSTANCE_NAME DATABASE_ROLE

OPEN std11203 PHYSICAL STANDBY

SQL> select group#, sum(bytes/1024/1024)"Size in MB" from v$log group by group#;

GROUP# Size in MB

     1         50
     2         50
     3         50

SQL> select group#,sum(bytes/1024/1024)"Size in MB" from v$standby_log group by group#;

GROUP# Size in MB

     6         50
     4         50
     5         50
     7         50

Check if the parameter standby_file_management is set to AUTO or MANUAL on standby database. If it is not set to MANUAL, then set it.

SQL> show parameter standby_file_management

NAME TYPE VALUE

standby_file_management string AUTO

SQL> alter system set standby_file_management=manual;

System altered.

SQL> show parameter standby_file_management

NAME TYPE VALUE

standby_file_management string MANUAL

On the primary database:

Check the status of the Online Redo Logs and resize them by dropping the INACTIVE redo logs and re-creating them with the new size.

SQL> select group#,status from v$log;

GROUP# STATUS

     1 INACTIVE
     2 INACTIVE
     3 CURRENT

Here you can see that Online Redo Log groups 1 and 2 are INACTIVE. Hence we can drop them and re-create with the new size.

SQL> alter database drop logfile group 1;

Database altered.

SQL> alter database add logfile group 1 size 100M;

Database altered.

The files will be created in either the default or current directory of the database server, depending upon your operating system.

Here it would be created in fast_recovery_area since it is already configured.

Use can fully specify filenames of new log members to indicate where the operating system file should be created.
for example:
ALTER DATABASE ADD LOGFILE GROUP 1 ('/u02/oradata/prm11203/redo01.log') SIZE 100M;

SQL> select group#,status from v$log;

GROUP# STATUS

1 UNUSED
2 INACTIVE
3 CURRENT

SQL> alter database drop logfile group 2;

Database altered.

SQL> alter database add logfile group 2 size 100M;

Database altered.

SQL> select group#,status from v$log;

GROUP# STATUS

1 UNUSED
2 UNUSED
3 CURRENT

Now that Online Redo Log Groups 1 and 2 are resized and the status of Group 3 is CURRENT, switch logfiles manually until Group 3 becomes INACTIVE.

After log switches, we can check the Status of Group 3

SQL> alter system switch logfile;

System altered.

SQL> select group#,status from v$log;

GROUP# STATUS

     1 CURRENT
     2 UNUSED
     3 ACTIVE

SQL> alter system switch logfile;

System altered.

SQL> select group#,status from v$log;

GROUP# STATUS

     1 ACTIVE
     2 CURRENT
     3 ACTIVE

SQL> alter system checkpoint;

System altered.

SQL> select group#,status from v$log;

GROUP# STATUS

     1 INACTIVE
     2 CURRENT
     3 INACTIVE

Now that Group 3 is INACTIVE, we can drop it and re-create it with the new size.

SQL> alter database drop logfile group 3;

Database altered.

SQL> alter database add logfile group 3 size 100M;

Database altered.

Now, we have resized all the Online Redo Logs on the Primary Database from 50M to 100M.

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$log group by group#;

GROUP# size in MB

1 100
2 100
3 100

Moving on to the Standby Redo Logs on the Primary Database:

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$standby_log group by group#;

GROUP# size in MB

6 50
4 50
5 50
7 50

SQL> select group#,status from v$standby_log;

GROUP# STATUS

4 UNASSIGNED
5 UNASSIGNED
6 UNASSIGNED
7 UNASSIGNED

The status of the Standby Redo Logs (SRL) on the Primary database would be UNASSIGNED as they would be used only when the primary database starts behaving as a Standby (Switchover)
We can easily drop the UNASSIGNED SRLs and re-create them with the new size.

SQL> alter database drop standby logfile group 4;

Database altered.

SQL> alter database add standby logfile group 4 size 100M;

Database altered.
Repeat this for the remaining SRLs on the primary database and we can see below that all the SRL on the Primary database have been resized.

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$standby_log group by group#;

GROUP# size in MB

     6        100
     4        100
     5        100
     7        100

Moving on to the standby database:

SQL> select group#,status from v$log;

GROUP# STATUS

1 CURRENT
3 CLEARING
2 CLEARING

Lets try to drop Online Redo Log Group 2 as Group 1 is CURRENT status and it cannot be dropped.

SQL> alter database drop logfile group 2;
alter database drop logfile group 2
*
ERROR at line 1:
ORA-01156: recovery or flashback in progress may need access to files

Here above, we faced ORA-01156 error, which is self-explanatory. The recovery (MRP process) on the standby database is active and it needs to be cancelled before we drop any Redo log groups.

SQL> alter database recover managed standby database cancel;

Database altered.

Since the status of Group 2 is still clearing, lets clear it manually before dropping the group.

SQL> alter database clear logfile group 2;

Database altered.

SQL> alter database drop logfile group 2;

Database altered.

SQL> alter database add logfile group 2 size 100M;

Database altered.

SQL> select group#,status from v$log;

GROUP# STATUS

1 CURRENT
3 CLEARING
2 UNUSED

The same is the case with Group 3 whose status is CLEARING. We’ll clear it manually, drop it and create with the new size.

SQL> alter database clear logfile group 3;

Database altered.

SQL> alter database drop logfile group 3;

Database altered.

SQL> alter database add logfile group 3 size 100M;

Database altered.

To drop online redo log group 1 that is in status CURRENT, generate an archive on the primary database by switching logfile, and then clear the CURRENT online redo log group on the standby database, drop it and re-create it with the required size as done for groups 2 and 3 earlier.

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$log group by group#;

GROUP# size in MB

1 100
2 100
3 100

Resizing Standby Redo Logs on standby database:

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$standby_log group by group#;

GROUP# size in MB

4 50
5 50
6 50
7 50

SQL> select group#,status from v$standby_log;

GROUP# STATUS

4 ACTIVE
5 UNASSIGNED
6 UNASSIGNED
7 UNASSIGNED

Clear the SRL group whose status is ACTIVE as done earlier, drop the group and re-create them with the size same as that of the Online Redo Logs.

For the SRL groups whose status is UNASSIGNED, just drop the group and recreate them with the size same as that of the Online Redo Logs.

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$log group by group#;

GROUP# size in MB

1 100
2 100
3 100

SQL> select group#,sum(bytes/1024/1024)"size in MB" from v$standby_log group by group#;

GROUP# size in MB

4 100
5 100
6 100
7 100

Once all the Standby Redo Logs and Online Redo Logs have been resize on both Primary and standby database, set the STANDBY_FILE_MANAGEMENT to AUTO on the standby database and start the recovery (MRP) on standby database.

SQL> alter system set standby_file_management=auto;

System altered.

SQL> alter database recover managed standby database disconnect from session using current logfile;

Database altered.

SQL> select process,status,sequence# from v$managed_standby;

PROCESS STATUS SEQUENCE#

ARCH CONNECTED 0
ARCH CLOSING 66
ARCH CONNECTED 0
ARCH CLOSING 63
RFS IDLE 0
RFS IDLE 0
MRP0 WAIT_FOR_LOG 71
RFS IDLE 71
RFS IDLE 0

9 rows selected.

Primary:

SQL> select max(sequence#) from v$archived_log;

MAX(SEQUENCE#)

70

Standby:

SQL> select max(sequence#) from v$archived_log where applied='YES';

MAX(SEQUENCE#)

70

For RAC database :

Syntax to add /drop group are as Below

SQL>Alter database add standby logfile Thread group size <>M;

SQL>Alter database add logfile Thread group size <>M;

REFERENCES
NOTE:740675.1 - Online Redo Logs on Physical Standby
NOTE:1243177.1 - ORA-16401 and ORA-16055 reported in primary alert.log when redolog switch is over frequently