How to Multiplex Control Files in Oracle Database?

After this article, you will have the understanding of,

• How to add one or more control files in oracle database? 
• Why do we require control file multiplexing? 
• Why is it important to have multiple copies of control files in your oracle base?

Control files serve a very important role and are very crucial for database working because of the information stored inside them. You can't take the risk of losing your control file especially when the database is running. When database is properly shutdown, even if you lose your control file, you can recreate it without much trouble. But the general idea is to secure the control file but taking regular backups and also multiplexing the same. By multiplexing, we simply mean to keep multiple copies of the same file in different locations.

Overview to Oracle Instance Memory Structures - SGA Explained

What is SGA or System Global Area in Oracle Database? A complete explanation guide to Oracle Memory Structures? Various components of SGA Explained in detail.

SGA also known as Shared Global Area is a very important part of Oracle Memory Architecture. As I have mentioned in one of my previous posts regarding the Explanation of Oracle Database Server that SGA is the part of Oracle Instance which includes some memory components and some background process which work together to keep the Oracle Database Server running.

Overview to Oracle Process Architecture - Background Process Explained

What are the Background Processes that run in Oracle Server? What is their functionality?

Oracle Server uses multiple background processes which help in handling different processes simultaneously. These processes are capable of handling single user request or multiple user requests depending upon the environment need. These background processes are nothing but some consolidated functions which are handled by multiple database programs running for each and every user process. Background processes asynchronously perform I/O and monitor other Oracle Database processes to provide increased parallelism for better performance and reliability.

RMAN Incremental Backup for Rolling forward a Standby - Oracle Database

How to take backup while Rolling Forward the Standby - Oracle Database

What kind of backups are required to roll forward the standby database? Scripts required to take necessary backups for rolling forward a DR Site and bring it in sync with Primary.

rolling forward a standby using RMAN incremental backup

Clone/Refresh/Duplicate Database using RMAN Backup - No Recovery Catalog

Clone/Refresh Oracle Database using RMAN DUPLICATE without Recovery Catalog or Target DB

Create Test Database using RMAN Duplicate without Recovery Catalog

How to Transport Tablespace in Oracle Database?

Transport Tablespaces in Oracle Database 11g

How to transport a tablespace in Oracle database | Steps to transport a tablespace | Manual guide on how to transport a tablespace | how to check if a tablespace is transportable or not

Transport Tablespaces in Oracle Database 11g

ORA-01031: insufficient privileges - Oracle Database

ORA-01031: insufficient privileges in Oracle Database

What ORA-01031: insufficient privileges oracle error indicates? How to resolve ORA-01031 error in Oracle Database?

ORA-01031: insufficient privileges

ORA-25207: enqueue failed, queue is disabled from enqueueing - Oracle Database

ORA-25207: enqueue failed, ORA-06512: at "SYS.DBMS_AQ" in Oracle Database

ORA-25207: enqueue failed, ORA-06512: at "SYS.DBMS_AQ"

Find the storage structure when creating a table - Oracle Database

How to find the storage structure when creating a table - Oracle Database

How to know where my table gets stored when it is created? How to find the tablespace, extent, memory allocated information when creating an object in Oracle Database? How to investigate the storage structure in Oracle Database?

Find the storage structure when creating a table Oracle

RMAN-20230: datafile copy not found in the repository - Oracle Database

RMAN-03002 RMAN-20230 RMAN-06015 Errors while performing switch database to copy in Oracle Database

RMAN-20230: datafile copy not found in the repository

Possible network disconnect with primary database | Oracle Standby

Possible network disconnect with primary database in Oracle Standby Alert Log

Issue:

After starting the log shipping in Standby from Primary, the below mentioned warnings/errors started popping up in the Standby Alert log:

RFS[418]: Possible network disconnect with primary database

RFS[421]: Possible network disconnect with primary database

Thu Sep 21 11:07:50 2017

RFS[400]: Possible network disconnect with primary database

Thu Sep 21 11:07:53 2017

RFS[411]: Possible network disconnect with primary database

RMAN-03002 RMAN-06496 Errors in RMAN Restore - Oracle Database

RMAN-03002 RMAN-06496 Errors in Restore Operation - Oracle RMAN

RMAN-03002 RMAN-06496 Errors in RMAN Restore

ORA-12514: TNS:listener does not currently know of service - Oracle Database

ORA-12514: TNS:listener does not currently know of service requested in connect descriptor

How to resolve ORA-12514 error? Tips to resolve ORA-12514 error in oracle database.

ORA-12514: TNS:listener does not currently know of service

Script to see RMAN running jobs and to kill them - Oracle Database

 The below mentioned script helps you to find out already running RMAN operations (if any) in the database. You can modify the query as per the output you want to get but this particular one will show you the list of all the RMAN jobs which are currently in running state and are not yet completed. This query will also show you the jobs which might not be running because of manual cancellation but are still pending to be cleared up from the queue.

select sid, serial#, start_time, totalwork,  sofar, (sofar/totalwork) * 100 pct_done 
from v$session_longops
where totalwork > sofar
AND opname like 'RMAN%';

If you want to kill some particular RMAN Job which you do not want to exist in the database, use the below mentioned queries.

For Single Instance:

alter system kill session 'SID,SERIAL#' immediate;

In Oracle's multi-instance environment (Oracle RAC), it might happen that when you run the above mentioned query, it'll fail with the below mentioned error,

ERROR at line 1: 
ORA-00026: missing or invalid session ID

This is because in multi-instance environment, you need to specify the instance_id as well with the query. There are chances that the instance from where you are trying to kill the job is different from the instance from where the job has run.

For Oracle RAC (multi instance environments):

alter system kill session 'SID,SERIAL#,@instance_id' immediate;

Failed to request gap sequence notification in Alert Log - Oracle Database

CONTROL_FILE_RECORD_KEEP_TIME initialization parameter in Oracle Database

CONTROL_FILE_RECORD_KEEP_TIME initialization parameter

Read the Content of Redo Log using Logminer - Oracle Database

How to use Logminer in Oracle Database?

What is logminer in oracle database? How does logminer works? How to read the content of redo or archive logs in oracle database? Usage and Benefits of Logminer in Oracle Database.

Logminer in Oracle Database

Understanding System Monitor Process in Oracle Database

Quick reference to System Monitor (SMON) process in Oracle Database

What is a System Monitor SMON Process in Oracle Architecture and What it does?

System Monitor Process SMON in Oracle Architecture

Understanding Log Writer Process LGWr in Oracle Database

Quick Overview to Log Writer Process LGWr- Oracle Database

What is LGWr process in Oracle Database? What is the use of LGWr process and how it works?

Log Writer Process LGWr in Oracle Architecture

Understanding DBWr process and it's significance - Oracle Database

Quick reference to Database Writer Process (DBWr) in Oracle Database

What is a DBWr process? What is it's significance in Oracle Database? When and how this process is called?

Database Writer Process DBWr in Oracle Architecture

Catalog backup files in RMAN | Oracle Database

Catalog the backup files in Oracle RMAN Repository

How to Catalog files in Oracle RMAN Repository? How to add files in RMAN Catalog?

Recovery Manager Catalog Oracle Database