Tuesday, June 13, 2017

Exadata -- adding an additional hostname (with different domain name)

I'm writing this blog post, because I think the information that I will share with you below, can not be found on Oracle Support, as a whole. I mean, you can find your own way by filtering the information that you may gather from several documents and installation guides, but here is a filtered information obtained to achieve a specific purpose.

The purpose that I'm mentioning here is "adding additional hostnames (with an additional domain name, different than the current ones) to Exadata".

Note that, the Exadata that I' mentioning here is a Quarter Rack, generation 4 (X4-2). (Note that, the same logic applies almost for every Exadata versions )

The reason to have an additional hostname with a different domain name in Exadata, was actually  a business requirement, in this case.

In this specific case, a critical database was going to be migrated to the Exadata and the customer wanted this database to have specific local and remote listeners, which should have been listening the hostnames which had to have a different domain suffix than the domain name the Exadata compute nodes already had.

In order to have such an environment, we needed to go for a multiple scan configuration, and in order to have a multiple scan configuration, we needed to enable the free network interfaces of Exadata compute nodes, first.

There were 2 Exadata compute nodes in a 1/4 Rack.

Each node had 6 network interfaces.

Here is the interface list of an Exadata X4-2:

3 of these interfaces were already used.

eth0 -> management network
eth1 & eth2 ->  slaves of the bondeth0 device
The private interconnect was on infiniband.

So, the other 3 of these interfaces were free to use. (eth3, eth4 and eth5)

eth4 and eth5 was not ready to use. That is, the SFP transceiver modules for using these devices were not installed to the Exadata compute nodes. (This was actually normal, because these modules are purchased seperately)

Anyways, we decided to go with eth3, which was called as the out of the box additional network in almost all the Exadata related documentation.

Well.. We first needed to enable the eth3 interfaces on each of the exadata compute nodes. Then, we needed to create vips on them and configure an additional scan accordingly.

So, we put the following plan in action ->

  • Connect eth3 to the customer network switch (not to the infiniband switch) ,so the client connections can come to the database. 
  • Configure eth3 interface with IP, Subnet Mask and Gateway and make it up & running.
  • Set VIP hostnames for this new interface
  • Add these VIP hostnames in to DNS 
  • At this point, add an additional SCAN by following the MOS document - "12c: How to create additional SCAN/SCAN VIP  ( Doc ID 2138078.1 )" 

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