Oracle 11gR2 RAC SCAN ORA-12543: TNS:destination host unreachable

環境： Oracle 11gR2 RAC,  CentOS 5.6

透過SCAN訪問RAC database, 不時出現ORA-12543: TNS:destination host unreachable，經查只有一個scan listener可以訪問。
[oracle@rac7 ~]$ srvctl config scan
SCAN name: rac-scan, Network: 1/192.168.56.0/255.255.255.0/eth0
SCAN VIP name: scan1, IP: /192.168.56.10/192.168.56.10
然而
[root@rac7 ~]# vi /var/named/localdomain.zone

$TTL    86400
@       IN SOA  localhost root.localhost (
                                        42              ; serial (d. adams)
                                        3H              ; refresh
                                        15M             ; retry
                                        1W              ; expiry
                                        1D )            ; minimum
                IN NS           localhost
localhost       IN A            127.0.0.1
rac5            IN A    192.168.56.248
rac7            IN A    192.168.56.247
rac5-priv       IN A    192.168.56.5
rac7-priv       IN A    192.168.56.7
rac5-vip        IN A    192.168.56.105
rac7-vip        IN A    192.168.56.107
rac-scan        IN A    192.168.56.10
rac-scan        IN A    192.168.56.11
rac-scan        IN A    192.168.56.12
有三個scan ip地址


更改操作如下：

srvctl stop scan_listener
srvctl stop scan
切換到root使用者
/u01/app/grid/bin/srvctl modify scan -n rac-scan
/u01/app/grid/bin/srvctl config scan
/u01/app/grid/bin/srvctl modify scan_listener -u
/u01/app/grid/bin/srvctl config scan_listener
/u01/app/grid/bin/srvctl srvctl start scan_listener
再切換到oracle使用者
srvctl status scan
srvctl status scan_listener

測試 sqlplus system/oracle@RAC-SCAN:1521/racdb.localdomain
然後多次檢視select instance_name from v$instance;
 可知instance_name會變化。