Migration of EBS R12.2.4 from Redhat 6 to Redhat 7

[Tabrez]

Been Following your Forum from Long time and the Content you share is Gold my Friend..Thank you very Much

We are planning to migrate our Application Tier from Redhat 6 to Redhat 7 and our EBS version is R12.2.4 but our database is going to remain on Redhat 6 only due to few budget constraints . Can you please help on following things and the current setup is with 2node Forms and 2 node CM but we are going to configure HA for EBS which we are confused how to proceed with Virtual Host configuration.

1) Can we Proceed with Migration without cloning DB part and only clonning Application Tier as we are not Migrating Db Tier?

2) To configure HA for EBS do we need to configure 8 nodes (4 for primary + 4 for standby) to single database ?

Please help on this..


Regards,
Tabrez.

[ErmanArslansOracleBlog]

Hi Tabrez,

Thanks for your feedback.

In order to migrate the apps tier from Linux 6 to 7, you need to use cloning basically. you will run preclone, copy the files and run post clone. (ofcourse following the MOS .. there are some prereq actions both for the source and target)
--note that, if (only if) you will have the same hostnames for target apps nodes (as the primary) and if you use the exact same directory structure as the source, then you may copy and start the services without even doing postclone... But as I mentioned only if you can have the same hostnames as the source and same directory structure as the source..

As for your questions:

1)Yes.
2)For configuring a proper HA, you need to have at least a 2 node EBS RAC database + multi node apps tier.(shared or non-shared apps filesystem .. according to our choice)  
This is just for primary. .. All the nodes will connect to the same EBS DB, but that EBS DB should better be RAC , as we want to be active-active and fault tolerant..

For DR, you will need to have dataguard for replicating and synching the DB and a filesystem/or storage replication method for the apps tier.

[Tabrez]

Hi Erman,

Thanks for the update.

Few question on this:

1) Here we are Migrating only apps servers to RHEL 7 and a single node DB server will remain on the same server. Can we Clone only Application Server as Db will remain on the same host (RHEL 6) ?

2) On Application Tier  R12.2.4 we have 4 node ( 2 Forms + 2 Concurrent ) but it is not on  NAS now during migration can Migrate filesystem to NAS ..will it cause any issues?

3) While Configuring HA EBS apps servers can we configure apps servers on standby server and then switchover to Primary then configure EBS apps nodes ?


Regards,
Tabrez.

[ErmanArslansOracleBlog]

1)Yes. This is not even a mixed platform.. Just the OS levels are different. Platforms are the same.. Linux - Intel.. No problems with that. However, we don't recommend it generally.. Actually you should also plan upgrading your DB in the near, because one way or another you will need to upgrade the DB to 19C and it requires Linux 7..
Well, again It is better to be at the same OS distribution and same OS level in all the nodes.. But as I said, it will not be a problem when your apps tier is on Linux 7 and your db tier is on Linux 6. Ofcourse as long as those Linux Operating systems are certified with your EBS release..

Also see -> https://blogs.oracle.com/ebstech/can-ebs-nodes-be-at-different-operating-system-levels

2)It can be done and it won't cause issues -- but you need to do it properly. Follow the MOS note related with the Sharing EBS filesystem.. Basically you will configure the shared filesystem on your target apps nodes and do a proper cloning aligned with the sharing EBS filesystem approaches..

3)If I understand you correctly, Yes...

Run adpreclone on primary
Replicate the apps nodes and make them continously sync from the primary
Then do a proper EBS aware db switchover(-> dataguard based sync standby)
Run postclone on db tier
Then do an apps switchover(just switch the direction of the related replication process)
run postclone on apps (if the filesystem paths and hostname are not the same as the source)..
Do any other custom actions if they are necesssary on your env and finally continue with your new environment, it will be your new primary...

But! review EBS 12.2 installation notes (MOS Notes) for using the apps nodes on Linux 7 . There are thing you need to do as prereqs .. on Linux 7 servers I mean.