Change in IP

d27m11y
d27m11y used Ask the Experts™
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We are moving from Oracle to Exadata. In this scenario, do we expect change in Server Ipaddress and DNs names or just IP addresses.

Please help!
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Top Expert 2008

Commented:
Moving only the data to Exadata doesn't change the IP address of the instance.
But moving the Oracle instance to Exadata  (in the Computing Node of Exadata machine) will need a new IP address (in case of RAC - 4 new IP addresses - 1 for VIP and 3 for SCAN IP's)

Author

Commented:
What is VIP and Scan IPs. Is there any link that I can find more about it.

Also, we currently have One Primary db and two ready only on active dataguard and have wide ips configured for all of these.  When we move to exadata, we are planning to have only one ready only db. How can we configure wide ip so that clients don't have any impact.

Please advise.
Top Expert 2008
Commented:
A VIP is a virtual IP for a specific server node in the cluster.
 
Should that server node fail, this VIP is transferred to another server node in order to still provide network connectivity for clients using the address of the failed server node. VIP in other words provides high availability as despite a server node failing, network communication to this node will still be supported by another node via the failed node's VIP.

 
SCAN is a virtual hostname for the cluster. On a 10 node cluster, there will be 10 virtual IP addresses with 10 virtual hostnames - which means that many clients will need to know and use all 10 VIPs in order to make load balanced, or high availability, or TAF, connections.
SCAN replaces this on the client side - by providing the client with a Single Client Acces Name to use as oppose to 10 VIPs. The SCAN listener service knows all cluster services - and can redirect the client to the appropriate VIP listener where the requested service is available.
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Top Expert 2008

Commented:
VIP Address

http://docs.oracle.com/cd/B28359_01/rac.111/b28254/admcon.htm

Virtual internet protocol address (VIP)
A virtual IP address is an alternate public address that client connections use instead of the standard public IP address. To configure VIP addresses, you need to reserve a spare IP address for each node, and the IP addresses must use the same subnet as the public network.
If a node fails, then the node's VIP address fails over to another node on which the VIP address can accept TCP connections but it cannot accept Oracle connections. Generally, VIP addresses fail over when:
•      The node on which a VIP address runs fails
•      All interfaces for the VIP address fail
•      All interfaces for the VIP address are disconnected from the network
Clients that attempt to connect to the VIP address receive a rapid connection refused error instead of waiting for TCP connect timeout messages. You configure VIP addresses in the address list for your database connection definition to enable connectivity.
VIP and SCAN

https://community.oracle.com/thread/2595729

Author

Commented:
What changes should be made on Client's side who connect to Oracle DB who use tnsnames.ora,

Should the host in tnsnames.ora be replaced with dnsname of SCAN as SCAN includes the nodes of DB Servers with different IP addresses.

Any input in wideip set up?
Top Expert 2008
Commented:
The SCANs IP (any of them) are the input point to the RAC nodes. SCAN IP forces the Listener to look for a node of the RAC to connect with in balanced manner. The Listener investigates the current load of the nodes and decides which node is the lowest loaded node.

Author

Commented:
If that is the case. In the scenario moving from Oracle to Exadata on RAC, what would be the change in tnsnames.ora.
Top Expert 2008

Commented:
Single Instance or RAC installation?

Author

Commented:
RAC installation.
Top Expert 2008
Commented:
For RAC I will recommend to point two IPs:
1) For administration of every node one VIP for every node. This Ip points directly to node instance (if it is on!!!!!!!!)
2) For the Applications 1 of the SCAN IPs. The Listener will investigate the load of the nodes and direct the connection to the least loaded node.

Please refer also the RAC installation guide - follow strictly the number and properties of the different IPs.

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