Monday, 28 May 2018

Convert / Migrate single Instance database to RAC database manually

Detailed steps to convert / migrate your single instance Oracle 10g Database to 2 node RAC database manually. The current environment is a single Instance Oracle 10g Database running on a local storage. We would migrate it to shared storage with 2 RAC instances.

1.  Preliminary Configuration and Verification
2.  Migrate the existing database to shared storage (Raw devices / ASM)
3.  Install the CRS Software
4.  Install Oracle RAC Software
5.  Configure Listeners, tnsnames files
6.  Modify/Create Initialization parameter, Password files
7.  Start the first Instance
8.  Create RAC data dictionary views
9.  Create Undo tablespace, Redo log files
10. Bring up the Second RAC Instance
  11. Verify status of RAC processes/Services

- Install the Oracle Clusterware and Oracle RAC Database software on nodes
- Copy/Edit original init file as init$SID1.ora and init$SID2.ora
- Make sure SID, listeners, tnsnames, profile, password file are correct on both nodes

Sample init, tnsnames, listener files

Moving DB to shared storage:
Create pfile from spfile on original instance, if using spfile
Shutdown original instance
Copy only datafiles on raw devices:

dd if=/oradata/file_name of=/dev/raw/raw5

Start instance in mount state

Rename datafiles:
alter database rename file '/u01/app/oracle/oradata/test10g/users01.dbf' to '/dev/raw/raw7';
alter database rename file '/u01/app/oracle/oradata/test10g/temp01.dbf' to '/dev/raw/raw8';

Alter database open;

ADD LOGFILES on shared storage:
(Don't try to drop active group)
select group#, bytes, status from v$log;
select group#, member from v$logfile;

alter database add logfile group 4 '/dev/raw/raw13' size 128M;
alter database add logfile group 5 '/dev/raw/raw14' size 128M;

select group#, status from v$log;
alter system switch logfile;

alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 3;
select group#, bytes, status from v$log;

Alter database backup controlfile to trace;
shutdown immediate;

Edit init file and give raw location of controlfiles (rename spfile so Instance do not start using spfile)

Recreate controlfile;
Alter database open;
shutdown immediate;

Now Database has been moved to shared storage on original instance.

Now Start DB from RAC instance 1:
(Make sure RAC instances have the latest init file)

START the first instance

Add tempfile

Create RAC dictionary views:
shutdown immediate

Add db to cluster using srvctl:
srvctl add database -d -o $ORACLE_HOME
srvctl add instance -d test10g -i test10g1 -n rac1
srvctl add instance -d test10g -i test10g2 -n rac2
srvctl start instance -d test10g -i test10g1

alter database add logfile thread 2 group 1 '/dev/raw/raw15' size 128M;
alter database add logfile thread 2 group 2 '/dev/raw/raw16' size 128M;
alter database enable thread 2;

create undo tablespace UNDOTBS2 datafile '/dev/raw/raw10' size 25M;

Start 2nd instance:
srvctl start instance -d test10g -i test10g2

Verify the RAC services:
crs_stat -t
srvctl status database -d test10g
srvctl stop database -d test10g
srvctl start database -d test10g

select instance_number instance#, instance_name, host_name, status from gv$instance;

You have now converted your single instance database to a 2 node RAC database.

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