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4 Replies Latest reply: Oct 21, 2012 8:54 AM by 864103 RSS

tnsnames in rac 11g.2

864103 Newbie
Currently Being Moderated
hi all ,

i have oracle 11g .2 with rac and asm in linux 5
i have 2 nodes

can you please advice in my question below :

i read of SCAN which is provide single name for client to access the database and tnsnames for client
will be not change if you add or remove other node and we have 2 option to define the scan
1.DNS. 2.GNS
the first one is by ask the netwrok admin to create name to resolve 3 ips,and the second on when you have dhcp
and we have another option is be define only one ip in hosts file for each node , i think this is what i have due the below ,the command below must be retain 3 ips

[oracle@ccbs01 admin]$ nslookup ccbs-scan
;; connection timed out; no servers could be reached

vi /etc/hosts
x.x.x.120 ccbs-scan.localdomain ccbs-scan and this line is define in 2 node (2 server one ccbs01,ccbs02)

my question is when we have client with same version 11.2
connect to db and one node is unavailable is it switch to another node due to the tnsnames include scan ip
x =
(ADDRESS = (PROTOCOL = TCP)(HOST = x.x.x.120)(PORT = 1521))
(SERVICE_NAME = x.domain)

cuz i read the scan do the load balancing and failover???

one more think


have vip x.x.x.115

have vip x.x.x.116

when i turm off the ccbs 01

in ccbs 02

ifconfig -a
return 115 and 116
means the vip switch to another node????

last question please

when we have database 11g.2 rac but the client is older
the advantage of scan will be loss till add the below

(ADDRESS=(PROTOCOL=tcp)(HOST= x.x.x.115)(PORT=1521))
(ADDRESS=(PROTOCOL=tcp)(HOST= x.x.x.116)(PORT=1521))

115,116 vip for 2 node

but the error appear ora-12154 ????

i want to use the above tnsnsames in other client and use 2 parameter to switch to another address without delay the user if first ip is corrupted???

advice please
  • 1. Re: tnsnames in rac 11g.2
    sb92075 Guru
    Currently Being Moderated
    861100 wrote:

    but the error appear ora-12154 ????
    ORA-12154 ALWAYS only occurs on SQL Client & no SQL*Net packets ever leave client system
    ORA-12154 NEVER involves the listener, the database itself or anything on the DB Server.
    ORA-12154 occurs when client requests a connection to some DB server system using some connection string.
    TNS-03505 is thrown by tnsping & is same error as ORA-12154 thrown by sqlplus or others.
    The lookup operation fails because the name provided can NOT be resolved to any remote DB.
    The analogous operation would be when you wanted to call somebody, but could not find their name in any phonebook.
    The most frequent cause for the ORA-12154 error is when the connection alias can not be found in tnsnames.ora.
    The lookup operation of the alias can be impacted by the contents of the sqlnet.ora file; specifically DOMAIN entry.
    TROUBLESHOOTING GUIDE: ORA-12154 & TNS-12154 TNS:could not resolve service name [ID 114085.1]
  • 2. Re: tnsnames in rac 11g.2
    864103 Newbie
    Currently Being Moderated
    thanks ,but what about other question ,sorry for butting this thread here.
  • 3. Re: tnsnames in rac 11g.2
    864103 Newbie
    Currently Being Moderated
    any update please .
  • 4. Re: tnsnames in rac 11g.2
    864103 Newbie
    Currently Being Moderated
    thanks i found all answer of my question , but i have one question please

    i know i can reallocate the scan ip manual can you please tell me how , another rac with two node
    one master and other is slave can i switch between these means
    node 1 is master node 2 is salve can i do node 2 as master but without restart the server???thanks in advance.


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