To check the master node in RAC environment

In 3 node RAC setup,In initial stage–node 3 is the
master node.

[oracle@host01 ~]$ cat
$ORACLE_HOME/log/host01/cssd/ocssd.log
|grep ‘master node’ |tail -1

2016-09-24 10:14:36.949:
[ CSSD][2778696592]clssgmCMReconfig: reconfiguration
successful, incarnation 248954981 with 3 nodes, local node number 1, master
node number 3

[root@host02 cssd]# cat
$ORACLE_HOME/log/host02/cssd/ocssd.log
|grep ‘master node’ |tail -1

2016-09-24 10:14:36.953:
[ CSSD][778696592]clssgmCMReconfig: reconfiguration
successful, incarnation 248954981 with 3 nodes, local node number 2, master
node number 3

[root@host03 ~]# cat
$ORACLE_HOME/log/host03/cssd/ocssd.log
|grep ‘master node’ |tail -1

2016-09-24 10:14:37.001:
[ CSSD][778700688]clssgmCMReconfig: reconfiguration
successful, incarnation 248954981 with 3 nodes, local node number 3, master node number 3

If I take the OCR backup
right now, it will be taken by node3 (master node).

[root@host02
cssd]# ocrconfig -manualbackup

HOST3

2016/09/24 09:54:48 /u01/app/11.2.0/oracle/cdata/cluster01/backup_095448.ocr

Let us check crsd logs of various nodes, looking for the string OCR
MASTER.Note that node3 is the master node presently.

[oracle@host01 crsd]$ cat
/u01/app/11.2.0/oracle/log/host01/crsd/crsd.log
|grep ‘OCR MASTER’ | tail -1

2016-09-24 10:15:01.403: [ OCRMAS][2877356944]th_master: NEW
OCR MASTER IS 3

[root@host02 crsd]# cat
/u01/app/11.2.0/oracle/log/host02/crsd/crsd.log |grep ‘OCR MASTER’ | tail -1

2016-09-24 10:15:03.561: [ OCRMAS][876976016]th_master: NEW
OCR MASTER IS 3

[root@host03 crsd]# cat
/u01/app/11.2.0/oracle/log/host03/crsd/crsd.log |grep ‘OCR MASTER’ | tail -3

2016/09/24 10:11:18.499: [ OCRMAS][877467536]th_master:13: I AM THE NEW OCR
MASTER at incar 44. Node Number 3

Let me reboot node3 and check which
node is assigned the master node now.

[root@host03 ~]# init 6

check the ocssd logs on the remaining
two nodes (node1 and node2) for the string ‘master node’ and note that
node 1 is the master node.

[oracle@host01 root]$ cat
$ORACLE_HOME/log/host01/cssd/ocssd.log |grep
‘master node’ |tail -1

2016/09/24 10:09:23.522:
[ CSSD][2778696592]clssgmCMReconfig: reconfiguration
successful, incarnation 248954982 with 2 nodes, local node number 1, master
node number 1

[root@host02 cssd]# cat
$ORACLE_HOME/log/host02/cssd/ocssd.log
|grep ‘master node’ |tail -1

2016/09/24 10:09:23.502:
[ CSSD][778696592]clssgmCMReconfig: reconfiguration
successful, incarnation 248954982 with 2 nodes, local node number 2, master node number 1

As can be seen from ocssd logs of the
remaining two nodes, node1 has become the master now.

Now If I take the OCR
backup, it is taken by node1 while earlier backups were taken by node3 which was
the then master.

[root@host02 cssd]# ocrconfig -showbackup

host03 2016/09/24 09:54:48 /u01/app/11.2.0/oracle/cdata/cluster01/backup_095448.ocr

[root@host02 cssd]# ocrconfig
-manualbackup

host01 2016/09/24 10:12:29 /u01/app/11.2.0/oracle/cdata/cluster01/backup_101229.ocr

host03 2016/09/24
09:54:48 /u01/app/11.2.0/oracle/cdata/cluster01/backup_095448.ocr

Let us check crsd logs of
various nodes, looking for the string OCR MASTER

[oracle@host01 crsd]$ cat
/u01/app/11.2.0/oracle/log/host01/crsd/crsd.log
|grep ‘OCR MASTER’ | tail -1

2016-09-24 10:08:45.884: [ OCRMAS][877356944]th_master:13: NEW OCR MASTER IS 1

[root@host02 crsd]# cat
/u01/app/11.2.0/oracle/log/host02/crsd/crsd.log
|grep ‘OCR MASTER’ | tail -1

2016-09-24 10:08:45.364: [ OCRMAS][876976016]th_master: NEW
OCR MASTER IS 1

[root@host03 crsd]# cat
/u01/app/11.2.0/oracle/log/host03/crsd/crsd.log
|grep ‘OCR MASTER’ | tail -1

2016-09-24 10:12:20.282: [ OCRMAS][877422480]th_master: NEW
OCR MASTER IS 1

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